UK’s Air Defence C2

The purpose of this paper is to identify requirements for the command and control (C2) of the British Army’s ground-based air defences (GBAD) within an overarching integrated air and missile defence construct. The context is that the Ministry of Defence is developing an integrated air and missile defence strategy, and the army is starting work supporting its Land GBAD programme. This paper seeks to outline the trajectory of the future air threat environment, as well as the components critical to meeting that threat, thereby deriving requirements for the C2 construct within which the UK’s GBAD will operate.

The future threat environment is characterised by diversifying and converging threats. Historically, air threats have been optimised by their range and cost to strike targets at varying depths, and have largely fallen into two categories: systems that seek to evade defences by flying low to avoid detection; and those that fly fast at high altitude. Defensive systems had therefore been optimised to maximise their probability of successfully intercepting the specific threats aimed at the targets they were defending. Increasingly, these categories are being blurred, both in terms of the targets against which munitions are assigned, and their flight characteristics. The result is that future air defences must be designed to maximise their efficiency as a system, allocating appropriate interceptors against simultaneous, multiple threats. The sustainability of an air defence system is therefore increasingly determined by C2 efficiency. The challenge is how to establish a robust, layered air defence capability that can identify, classify and assign the most appropriate mechanism to defeating complex salvos.

In order to track these diverse threats, the force must avoid being dependent on a small number of dedicated ground-based radars, which can be suppressed, or isolated and deceived. Instead, the air defence system must be able to fuse and integrate data tracks of varying quality and sensitivity from across the joint force’s sensors. This will include both radar on assets such as the E-7 Wedgetail and the F-35, which are optimised to track air threats, as well as sensors of opportunity normally focused on other targets. Acoustic sensors, for example, are likely to proliferate across land formations, intended to identify the source of fire. These systems are also able to provide tracks for low-flying air threats, if the data can be accessed. Accessing such data requires GBAD C2 to be bearer agnostic, and able to ingest data of varying kinds, delivered by a multitude of means. It will also be necessary for the system to be able to integrate new kinds of sensor and effector, either as new capabilities are fielded, or as novel capabilities are brought to bear in response to evolving adversary tactics.

These characteristics are especially important because UK GBAD systems are not currently equipped to be able to defeat many kinds of air threat. UK ballistic missile defences are operated solely by the Royal Navy, for example. Wherever the UK deploys, whether alongside NATO Allies or partners further afield, it must be able to contribute to and benefit from both joint sensors and effectors, and multinational C2. The diversity of UK partners with whom the UK – as a force that is expeditionary by design – would need to integrate means that the C2 architecture must be able to publish tracks to subscribers without sharing source code.

It is noteworthy that the UK currently lacks GBAD C2 capacity. 7 Air Defence Group has a very small cadre of personnel who might be considered professional air defenders, since the career structure in the Royal Artillery does not keep many officers in this area for a sustained period. Interoperability, however, places a premium on experience in dealing with multiple systems, and so professionalising air defence and expanding liaison opportunities is critical. It is also important to note that the two regiments of 7 Air Defence Group are currently configured to be able to provide a C2 node at division. The UK, however, aspires to have a NATO Reserve Corps and two Divisions. It is also evident – given the lack of organic capabilities – that liaison functions across the joint force and multinational allies and partners are vital. 7 Air Defence Group currently lacks the mass to maintain this many C2 nodes.

A further requirement is that the air defence C2 architecture be modular and mobile, without a single point of failure. This is achievable, and decision support tools mean that it is likely to become more so over time. Nevertheless, the C2 system must support air defence coordination from multiple small cells, able to be packed up and moved rapidly.

Introduction

For decades, air defence has been a low priority for European NATO, which has been operating with uncontested air and fires superiority. The UK, meanwhile, despite maintaining a robust maritime air defence capability, has seen its ground-based air defence (GBAD) reduced in priority – a point best illustrated by the downgrading of the task from a brigade-level function with four regiments, to a joint headquarters commanding single-service-operated systems with two assigned regiments. Now, however, several concurrent factors have prompted a renewed focus on the importance of air defence.

To begin with, the modernisation and proliferation of highly capable Russian and Chinese air defences mean that NATO air forces must prioritise the suppression and destruction of these barriers before they can contribute directly to joint effects. This means that other elements of the force must be able to fight without air superiority – and potentially without any air cover – for limited periods. Furthermore, Iranian and Russian collaboration in developing and employing a wide range of threat systems (from low-end loitering munitions to cruise and quasi-ballistic missiles) means that air threats will remain a persistent concern, even with air superiority. A further challenge is that whereas air attack could previously be partly deterred through the psychological impact of the presence of a limited number of surface-to-air missile systems (SAMS), this cannot deter uncrewed strike systems, and consequently the credibility of a defence increasingly correlates with magazine depth and engagement efficiency.

The threat will manifest in two ways for land forces. The first is the risk of destruction at the tactical level when forces have engaged with an opponent. The second threat is that of air interdiction: the destruction of forces before they have joined the fight, or the disruption of their enabling rear area infrastructure and logistics. The risk of interdiction is one that will also be faced by other elements of the joint force, and in certain circumstances ground forces may help offset it for other force elements.

The relationship between the terminology of air attack and land concepts is a fluid one, determined by factors such as which formations are conducting the tactical battle (which determines the depths beyond which forces might be considered to have not joined the fight). The terminology used in this paper derives from that used in the context of the doctrine of AirLand Battle, where air activity beyond corps depth was typically treated as being operational. The basis for adopting this terminology is that the European theatre within which the British Army may have to operate is characterised by distances and, increasingly, force sizes similar to those of the Cold War. It is acknowledged, however, that the definition of operational depth may differ between expeditionary contexts.

There is also the question of which targets should be defined as strategic, as this term is typically reserved for the defence of either civil infrastructure or infrastructure with war-making potential (such as industry). Though the distinction is doctrinally valid, in the context of the UK, this paper presumes that the defence of both military and non-military targets in the homeland (where strategic targets reside) will be treated as part of a single zonally defined mission coordinated by HQ Air Command at High Wycombe, and thus the paper groups all defence of the homeland under the rubric of defence at strategic depth.

Against Russia, identified as the UK’s most acute threat by the Integrated Review, British forces in the field are likely to face air threats at every stage of their deployment. Operational rear areas will be held at risk by ballistic and cruise missiles, while forces will also be threatened by UAVs, rockets and crewed aviation as they approach the forward line of own troops (FLOT). Russia will also pose a long-range strike threat to the homeland. Other putative opponents, such as Iran or its proxies, will be less likely to threaten the homeland, but will still pose a robust and layered threat to fielded forces. Against Iran, which can disseminate strike capabilities to proxies, the threat will exist in both the operate and warfight postures, as illustrated by proxy-led attacks on US forces.

While the Royal Navy (RN) and the RAF can provide defences against cruise and (some) ballistic missiles for both the homeland and fielded forces, they are also required to provide – with limited fleets – their own organic force protection. Moreover, certain types of targets, such as many UAVs, which are relevant in a land context, are not ones the RN or RAF focus on countering in planning and training. Finally, a land component, depending on how far inland it is, may not be able to draw on naval support. The British Army’s GBAD capability should, then, be able to provide a degree of organic protection for fielded forces at the divisional level (and below) against short-range tactical threats. It should also, if needed, be able to reinforce national and Alliance capacity against some operational and strategic threats. The first goal can be achieved by capabilities that the army should itself be able to field. Drawing on joint force and allied assets will reinforce the effectiveness of these capabilities, but will not determine their ability to meet missions. For the second goal, the army must be integrated by design: it must find specific roles that it can play to reinforce any integrated air and missile defence (IAMD) system of which it is a part. Adding resilience to C2 mechanisms and optimising against a subset of threat types are the areas where the army can add greatest value to partners and the joint force in the army deep (300 km) and beyond.

In response to this challenge, the British Army has initiated a Land GBAD programme aimed at delivering short-range air defence (SHORAD), medium-range air defence (MRAD), counter-small aerial target and counter-small uncrewed aerial system (C-UAS) capabilities to protect the UK’s deployed forces and to potentially contribute to the defence of bases in the homeland. Beyond these core platforms, however, it is notable that as threats diversify and develop, the layered defences – comprising interceptors which operate at different altitudes and ranges (and with different characteristics in terms of seekers and payloads), as well as soft kill capabilities – will also need to adapt. Furthermore, while some of these capabilities will be specialised air defence assets, the sensors and effectors for others will be distributed across units. The C2 infrastructure for such an enterprise, encompassing both the technical means for coordinating assets (control) and the organisational structures and authorities which determine their allocation against tactical tasks (command), needs to be robust, but also adaptable, such that it can integrate a wide range of sensors and effectors.

This paper outlines the diversity and trajectory of threats that the Land GBAD programme will need to manage, the sensors and effectors it will need to coordinate, and the requirements this imposes for connectivity and decision points to be enabled. The purpose of the paper is to identify requirements for a suitable C2 architecture to both support the short-term air defence capabilities to be fielded by the British military, and to coordinate a developing set of systems as novel effectors become available and greater connectivity across the force expands the range of sensors that can be leveraged.

The evidence base for this paper is diverse. Firstly, it relies on the technical examination of Russian and Iranian threat systems employed in the Middle East and Ukraine. This includes examination of all classes of munitions and components of key platforms, mainly recovered from the battlefield, including Kh-47M2 Kinzhal aero-ballistic and 9M723 Iskander-M quasi-ballistic missiles. It also draws on the experience of observing the evolution and coordination of the Ukrainian Air Defence Network over the course of the war, and lessons derived from the Air Defence Working Group of the Ukrainian General Staff. In addition, the paper relies on field observation of British air defence capabilities in operation, of NATO air defence C2 in operation, and of experimental capabilities for both attack and defence in the UK, the US and NATO. The research is also based on participation in live exercises in the US, where novel systems and C2 tools were tested, and on interviews with scientific technical personnel, industry and commanders of air defence units. Because of the sensitivity of much of the underlying data, the report itself outlines the concepts, rather than the technical details of the requirements, but it is informed by hard data. The paper is divided into three chapters: the first examines threats; the second analyses sensors and effectors; and the third outlines the implications for the C2 capabilities needed to stitch these sensors and effectors together as an integrated system.

I. Charting a Diversifying Threat Landscape

To make any assessment of the requirements for the C2 of the British Army’s future GBAD, it is necessary to examine the threats against which British forces must protect themselves (and others). The threat landscape may be broken into two problem sets. First, there is the requirement to protect against tactical threats targeting deployed forces. Second, there is the requirement to protect strategic and operational targets, including sea ports and air ports of embarkation and sea ports and air ports of debarkation (SPODs and APODs), bases, and headquarters from the corps level and above. There is also – per the 2023 Defence Command Paper – an imperative to protect critical national infrastructure (CNI) and centres of habitation from adversary strikes, but as regards GBAD C2, this is a similar problem set to the defence of targets in operational depth.

These problem sets already existed during the Cold War, but they have converged in recent years. During the Cold War, the primary conventional air threat to frontline forces was Warsaw Pact aviation, while cruise and ballistic missiles such as the OTR-23 Oka were largely prioritised for targets in operational depth, such as airbases. Missiles were useful against a narrowly defined set of static and soft targets. Improvements in the accuracy of cruise and ballistic missiles mean that they can now be used both against tactical targets and against a wider range of operational and strategic targets, allowing them to threaten several military targets, in tandem with aircraft. In effect, well-defined threat categories which could previously only be used at the tactical, operational or strategic levels have converged as a function of increasing accuracy. Meanwhile, capabilities such as loitering munitions and one-way attack UAVs have, given their low cost and different flight profiles, added another dimension to this threat landscape. Despite this, the missions of defence at each level of warfare still differ, and the UK’s GBAD programme must have a C2 architecture that controls an appropriate mix of sensors and effectors to function both across different parts of the battlespace and across the continuum from competition to conflict. This chapter will first explore the diversifying kinds of threat system, and then consider how they manifest at tactical and operational depths.

Air and Missile Threats in the Future Operating Environment

Historically, air threats could be divided according to two parameters: altitude and speed. Although higher-flying threats such as ballistic missiles were faster, they could be detected earlier and followed predictable parabolic trajectories, whereas more manoeuvrable threats capable of flying at lower altitudes, such as aircraft and cruise missiles, were slower but harder to detect.

This binary categorisation remains valid, but is now complicated by two additional factors. The first is the emergence of weapons which straddle the categories of high speed and comparatively low trajectories, including supersonic and hypersonic cruise missiles and hypersonic glide vehicles (HGVs); quasi-ballistic and aero-ballistic threats which fly at lower altitudes than traditional ballistic missiles also fit within this category. The second factor is the emergence of especially slow and low-flying objects, such as UAVs, which fly at speeds that would normally see objects excluded from the Doppler gate of radar.

This target complexity means that the attendant two-tier categorisation of sensors and effectors – with upper-tier systems interdicting fast, high-altitude targets and lower-tier systems engaging their slower counterparts – is now being challenged. A system may, for example, need to track a fast-moving target across multiple altitude brackets. This complexity of air threats is compounded by the near ubiquity of electronic warfare (EW) and decoying. In Ukraine, radar decoys have been deployed by the 3M-14 cruise missile, the 9M723 quasi-ballistic missile, and by groups of UAVs (with one UAV acting as a decoy). The detection and classification of complex targets will require the fusion of data from a broader variety of sensors to better contend with threats built to confound radar-centric defensive systems. Self-contained systems built around dedicated radar optimised against specific threats must thus be integrated both with each other and with other sensor categories.

The second challenge to existing air and missile defence systems is the risk of suppression and destruction. While this capability was once the province of the stronger air force, conflicts such as the ongoing war in Ukraine have illustrated that a state without air superiority can still suppress an opponent’s GBAD by leveraging the growing accuracy of, among other things, surface-to-surface threats cued by UAVs. Moreover, even weaker air forces can use standoff capabilities to pose a risk from within the relative safety of their own GBAD networks.

The third challenge is that of mass. The gulf between capabilities which can be used at scale and more bespoke precise capabilities is shrinking. Modifications to the guidance of previously “dumb” systems can increase their accuracy by an order of magnitude. In addition, capabilities such as loitering munitions can provide a cheap avenue with which to strike targets with precision.

In terms of suppression, capabilities such as Spear 3 and other precise air-launched missiles will be the most severe threat for GBAD. At present, Russia does not possess capabilities equivalent in sophistication to Spear 3, although it does use the Kh-31 in this role to some effect. In the future, Russia may obtain advanced air-launched effects from its growing collaboration with China, such that People’s Liberation Army Air Force capabilities must be a planning assumption for UK GBAD C2. The challenge posed by these capabilities is that they are specifically tailored to striking GBAD systems, are fast, manoeuvrable, can utilise an aircraft’s active electronically scanned array (AESA) radar to course correct and engage moving targets, and can therefore constrain air defence tactics. Air defences must unmask and engage other air-launched threats, but in doing so, GBAD systems risk falling victim themselves to munitions tailored for SEAD/DEAD (suppression or destruction of enemy air defences).

This threat will be compounded by the emergence, as launch platforms, of very low observable (VLO) aircraft with significantly reduced radar cross-sections. It is likely that even those states without access to high-end stealth technologies will be able to produce aircraft that can push further into defended airspace before becoming trackable. This will accelerate if there is a proliferation of uncrewed combat aerial vehicles (UCAVs), as their shapes can be far “stealthier”, owing to the lack of a crew compartment and associated life-support systems. These stealth profiles, combined with EW, make it possible for air targets to come much closer to defensive radar than is comfortable for defenders, which will be a particular challenge as the effectors carried gain range.

There is also a threat of destruction by surface-to-surface fires. Missile systems such as the Iskander and Tochka-U and multiple-launch rocket systems (MLRS) such as the GMLRS (guided multiple-launch rocket system) have demonstrated their utility in the context of DEAD missions at divisional depth (and beyond, for the Iskander). When cued in by UAVs as part of what in Russian parlance would be called a reconnaissance-fires complex (for MLRS) and a reconnaissance-strike complex (for missiles), such capabilities can strike mobile SAMS within minutes, particularly close to the FLOT, where UAV coverage is greatest.

The second challenge that air defenders will face is a shrinking delta between capabilities which can be used en masse and those which are more precise. Previously inaccurate threats – including air-launched glide bombs and rockets – are likely to increase in accuracy by an order of magnitude. This, in turn, will make it possible for putative opponents to achieve lethal effects with platforms which might previously have represented a marginal threat.

This threat will likely emanate from adversary fourth-generation fast air, with its reach extended by relatively cheap standoff weapons. Legacy air defence systems have demonstrated that they can pose sufficient threat to aircraft at medium altitude to significantly degrade the accuracy of delivered effects. Modern man-portable air defence systems (MANPADS) can, meanwhile, effectively deter penetration by fourth-generation fighters at low level, because of the unpredictability of the location of MANPADS teams. Finally, an adversary aircraft operating over the FLOT faces a considerable risk of being destroyed by defensive counter-air patrols. However, the nascent ability of fourth-generation aircraft to attack with large volumes of reasonably precise standoff munitions from within the safety of a friendly air defence network can alter this dynamic considerably.

The advent of guidance kits and glide kits, even at the most basic, is proving that inaccurate iron bombs can now achieve ranges of up to 70 km when lofted, and that they are likely to become highly accurate in the near future, with only limited investment. Although unsophisticated, these munitions pose a serious threat to static or point targets because they can have an explosive payload in excess of 500 kg and thus cause considerable damage; moreover, these munitions are cheap, plentiful and can be released in volume. Although they must be lofted from medium altitude (where the launch aircraft may expose itself) to achieve maximum range, the flight profile prior to loft may be lower and, if launched against targets in shallow depth, can offer a very narrow window for air defences to threaten the aircraft. Guidance kits can also be fitted to older, inaccurate surface-based systems to create a more precise capability – as Iran has done for Hezbollah’s unguided Zelzal-2 rockets, effectively transforming the 200 km-range rocket into a short-range ballistic missile (SRBM). This type of transformation could see the scale of the tactical ballistic threat increase by an order of magnitude.

Attack aviation such as the Russian Ka-52 helicopter provides another launch vector for massed guided and unguided fires. Though less capable of reducing its signatures, attack aviation is likely to remain a serious threat to tactical ground formations due to the ability to hover and operate at extremely low altitude, as well as terrain mask. To retain survivability, attack aviation aims to fire munitions with ranges in excess of 10 km, taking themselves out of the MANPADS threat envelope. Efforts are also underway to field air-launched effects – essentially UAVs and other complex weapons – launched from helicopters to enable the pilots to direct complex attacks on targets. As the cost of these munitions increases and the survivability of airframes diminishes, countries may reduce the emphasis placed on attack aviation, but for now the main threat they pose is that they can carry and orchestrate a wide range of effects with very little latency between launch and strike. For a commander, attack aviation offers the flexibility of being able to manoeuvre precise firepower quickly from point to point as an anti-tank reserve. While attack aviation may primarily be a threat at the edge, it can inflict disproportionate attrition on a manoeuvre element that is not effectively protected by GBAD.

The third challenge for future air defenders is that of timely threat detection and classification against complex targets. This will be driven by a convergence of the systems already discussed with threats such as cruise missiles, ballistic missiles, HGVs and loitering munitions. Each threat is optimised to reduce defenders’ warning times in different ways, meaning that solutions optimised against one are likely to be inapplicable against others. In themselves, most cruise missiles are large, and are usually subsonic for most of their flight. Given that they fly low, in dense air, supersonic flight limits their range, though supersonic cruise missiles such as the P-800 Oniks can still be effective out to 400 km. Hypersonic cruise missiles, which must carry both a rocket propulsion system and a scramjet engine to achieve hypersonic flight, are likely to be even more limited in their range, compared to comparably sized missiles. Though supersonic and hypersonic cruise missiles will be restricted in terms of range, manoeuvrability, and in some cases payload, they will be difficult to intercept and will have the kinetic energy on impact to penetrate hardened targets. They will pose a challenge at tactical depth and can also pose one at operational and strategic depths if a launch platform such as a cruise missile submarine (SSGN) escapes detection. Their cost, however, limits the number of targets that justify their use. Subsonic cruise missiles are a much more common threat. These are relatively easy to intercept, but are difficult to track, because of the complexity of their flight paths and the fact that they can employ penetration aids and accelerate at key phases to complicate engagements. Given their accuracy, cruise missiles must be engaged.

While most cruise missiles are difficult to find but relatively simple to intercept once tracked, ballistic missiles are easy to detect but are often difficult to intercept, due to their speed, and are likely to become more challenging targets. Short- and medium-range ballistic missiles are relatively easy to intercept at present, as illustrated by the success in testing of THAAD (Terminal High Altitude Area Defence), as well as by Saudi Arabia’s intercept rate against Houthi SRBMs with Patriot and Ukraine’s successes with Patriot against SRBMs and air-launched ballistic missiles. Longer-range missiles are considerably faster and thus harder to engage. Moreover, even SRBMs are becoming more survivable. Like cruise missiles, they are liable to dispense penetration aids, complicating targeting, with the caveat that they move fast enough to mean that a penetration aid can only provide a short window of protection. Furthermore, more and more ballistic missiles will adopt quasi-ballistic trajectories, defying simple interception mapping – as seen with the 9M723 and the North Korean KN-24. The separation of warheads from the missile body in the terminal phase on some ballistic missiles can create a further complication, as defensive systems must distinguish between the missile body and the warhead.

HGVs may be understood as combining the challenges posed by cruise and ballistic missiles. Ballistic missiles descend on their targets at hypersonic speeds, but because they fly with a high arc, they are visible to radar for much of their flight. An HGV, in contrast, may achieve a much shallower angle of attack and alter course, reducing the time available to plot its trajectory. HGVs – unlike air-launched ballistic missiles such as the Kinzhal – are unlikely to become cheap enough to be available in large numbers. This is partly because the speeds involved impose non-symmetrical friction on the missile surfaces, leading to a requirement for highly complex materials to be employed in the body of the munition.

Air defenders will face competing dilemmas, as they will be confronted by both missiles and loitering munitions. Loitering munitions may be understood as lower payload, simpler cruise missiles – they fly low and slow, usually carrying payloads below 40 kg (still sufficient to cause substantial damage to most tactical targets). Simple loitering munitions able to strike throughout operational depth can cost as little as $30,000. The trajectory of development for loitering munitions is likely to see several areas of growing sophistication, without significant increases in cost. First, loitering munitions are likely to attain improved hardening of their navigation systems. Second, the use of software-defined radios should enhance their ability to collaborate (there is a cost to the software development, but it does not lead to a massive increase in unit cost for hardware). It is also likely that, at a cost of around $100,000 per unit, loitering munitions can retain a command link and thereby have a full motion video guidance capability in their terminal phase, enabling strikes on mobile targets. Thirdly, the low speeds of loitering munitions and some UAVs mean that they can be sifted out by the Doppler gates of radar as clutter – as occurred with Russian Pantsir radar against Turkish TB-2 UAVs early in the conflict in Syria. Radar operating modes can be altered – Russia quickly did this in March 2022 – but this imposes cognitive load on operators (from clutter), and increases training burdens. Although loitering munitions can be brought down by crew-served weapons if shooters are properly positioned, having shooters in the right place is a significant C2 challenge.

The attack systems described above are all, in themselves, beatable. Collectively, however, they impose conflicting imperatives on a defensive architecture. For example, the task of engaging low-flying fast air requires a different set of sensors and effectors to that of intercepting VLO aircraft. Similarly, the interception of threat types that can be fielded en masse demands interceptors which can be expended at scale, while defence against cruise and ballistic missiles requires more expensive effectors with the manoeuvrability and sensor payload to engage these targets. The need to avoid suppression, particularly close to the FLOT, imposes a different dilemma. Avoiding suppression is best achieved through passive methods of detection, such as passive coherent location, as well as non-radar-based solutions. However, the delivery of track-quality data over wide areas still requires the use of active radar, at the risk of suppression or destruction.

Implications for Tactical Defence

Historically, air defence in tactical depth has primarily been concerned with penetrating aviation and strike aircraft. Cruise and ballistic missiles – being expensive and consequently scarce assets – have been a concern for operational headquarters and other higher-echelon targets. Because aviation and strike aircraft were necessarily even more expensive than cruise missiles, maximising the probability of kill (Pk) by deploying highly sophisticated air defence munitions was a sensible investment. Air defence thus became a question of maximising Pk, and extending range to be able to engage strike aircraft enablers. Tactics evolved around aiming multiple missiles at a given aircraft to force the pilot into sub-optimal trade-offs against differing threats. The effect of maximising Pk is not just that it makes attempts to strike tactical targets extremely dangerous, but that this in itself deters attempts, increasing the enablement necessary to prosecute strikes with a reasonable probability of scarce aircraft surviving. This therefore limits the number of sorties that can be mounted. North Vietnamese SAMS, for example, imposed a requirement on the US Air Force to generate some 80 combat aircraft to conduct a raid on a given target.

The approach of maximising the Pk of air defence systems is now being fundamentally challenged, for three reasons. Firstly, the range of threats to tactical formations is expanding to include threats which might previously only have been encountered with conventional payloads at the operational/strategic levels. Secondly, many classes of threat are drastically cheaper and thus more plentiful than legacy defensive missiles. The cost of defensive systems aimed at optimising Pk against high-end threats necessarily reduces the diversity of systems that can be afforded and deployed. For example, a hit-to-kill missile with an infrared (IR) seeker optimised for ballistic missile defence (BMD) in the upper atmosphere is not an ideal means of intercepting air-breathing and quasi-ballistic threats at altitudes where IR seekers do not work well at the high speeds achieved by BMD interceptors. Radar-equipped missiles with blast fragmentation warheads work well against air-breathing threats, but are a sub-optimal tool for BMD: each type of missile has a price in the millions of US dollars and is fired from a bespoke system. As high-end threats diversify, the characteristics of systems optimised for detecting and engaging them diverge, driving a tendency towards holding multiple missile types that are industrially expensive to develop and retain. For example, it has been estimated that a point defence of Guam with the layered defensive systems needed to counter the full spectrum of likely threats would cost $5 billion. The third challenge is that an air defence approach that prioritises the maximisation of Pk against high-end threats is more difficult to develop iteratively and quickly than the systems that are intended to spoof or otherwise degrade defensive efficiency. This means that in any conflict, the Pk of a system risks diminishing over time.

The measure of effectiveness at the tactical level, then, should not be the Pk of individual systems against specific threats, but rather the ability of the air and missile defence system as a whole to deliver enough protection within a given time period for specific tasks such as concentration for an attack. This is a departure from the metrics that predominated in the past, because capability is measured at the system level, not the platform level, and is bounded by time and by task. A high Pk in initial engagements is of limited value if the air defence system is exhausted through inefficient use of interceptors such that Pk subsequently collapses. To a significant degree, therefore, the effectiveness of an air defence system is increasingly determined by the capacity of the C2 system to allocate effectors against appropriate targets.

Threats in Operational and Strategic Depth

At the operational and strategic levels, in a European context, the scenario used to frame the discussion is a Russian Strategic Operation for the Destruction of Critically Important Enemy Targets. This is not the only context in which the UK can expect to employ its GBAD capabilities, but it is the one most likely to involve risks to targets at both operational depth and at strategic depth within the UK. Military targets likely to be prioritised by an adversary at operational and strategic depth include SPODs and APODs and command nodes at the corps echelon and above. Assets upon which the functioning of the joint force depends, such as airbases and CAOCs (combined air operations centres), are also likely to be targeted. In addition, critical civilian infrastructure, including power generation facilities, is likely to be targeted. These targets may not all be in significant depth, but a critical mass of them are likely to be rearward of the corps.

The threat environment at the operational and strategic levels is different from the tactical threat environment in several ways. On the one hand, the range needed to strike targets at depth and the payload requirements needed to inflict meaningful damage on facilities such as airbases limit the utility of many platforms which might be tactically useful. One-way attack UAVs, for example, can be useful as a terror weapon, but given their payload limitations (a Shahed-136 carries around 40 kg of explosive material), they have limited utility against critical targets that have appropriate protections, unless part of a complex strike where they are used for reconnaissance or to strike defence systems.

Up to 500 km, the threat at the operational level will be complex, combining SRBMs, cruise missiles, attack aircraft and UAVs. In many respects, this is similar to the tactical-level threat environment: the ranges involved, as well as the presence of protected or hardened high-value targets such as command posts and ammunition storage sites, will see the number of cruise and ballistic missiles at these depths increase relative to UAVs. A greater premium is likely to be placed on large payloads and a higher probability of penetration and the presence of high-value targets at these depths justifies more expensive forms of attack – which is why, for example, Ukraine has used Storm Shadow cruise missiles against operational-level targets, to much greater effect than its salvos of UAVs.

Beyond 500 km, and particularly at strategic depth, the ballistic threat picture will be circumscribed, as the most likely adversaries do not field large numbers of intermediate-range ballistic missiles (IRBMs). Russia, for example, has only the Kinzhal for use at intermediate ranges, having cancelled the RS-26 Rubezh IRBM. Moreover, even states with large numbers of ballistic missiles typically use them to enable other capabilities. For example, China intends to use its ballistic missiles to trap US aircraft in their hangars by cratering runways, enabling follow-on attacks by cruise missiles. For Russia, which has fewer intermediate-range ballistic options and needs to conserve these options for sub-strategic nuclear use, the need to use capabilities such as Kinzhal and the Kh-BD judiciously will be more acute. The most likely use cases for ballistic missiles involve either enabling the effective use of cruise missiles, or strikes upon command nodes. As such, the challenge beyond 500 km is in certain ways more bounded than the tactical challenge, and will largely revolve around cruise missiles enabled by a more limited number of medium-range ballistic missiles and IRBMs, which trap their targets or eliminate defensive systems that engage cruise missiles.

In some ways, the threat at the army deep and beyond is more potent. Since many targets likely to be deemed valuable at operational and strategic depth are static, it is simpler to achieve the convergence of different capabilities moving against them at different speeds. While this level of convergence against mobile targets is discussed at a theoretical level by militaries such as China’s People’s Liberation Army, it has already been demonstrated by Russia in its attacks on Ukraine’s energy grid, which have combined UAVs, cruise missiles and ballistic missiles.

Geography and force laydowns are a consideration in any European context. Most Russian threats to the UK homeland emanating from the Western Military District would need to traverse the airspace of several NATO members, raising the probability of intercept well ahead of their reaching the UK. Moreover, on this flank, the surface vessels of the Baltic fleet which serve as launch platforms for cruise missiles such as the 3M-14 Kalibr are not survivable in a full-scale conflict involving Russia and NATO. However, this is not to say that all approaches to the UK are equally well covered, with the assets under Russia’s Northern Fleet Joint Strategic Command (OSK Sever) in particular presenting a credible threat to the homeland, as they can strike from positions relatively close to Russia’s bastions. Over time, as NATO stands up a maritime component command in a crisis, the northern flank would also become comparatively more secure.

That said, some launch platforms for Russian strike capabilities are more survivable, and could theoretically conduct strikes against the UK, giving defenders very limited warning – for example, the Yasen-class SSGN, which is equipped with 40 vertical launching system (VLS) cells and which can launch a variety of cruise missiles, including the 3M-14 Kalibr and the hypersonic Zircon. Platforms such as the Yasen or the older but still quiet Akula class can, if they escape into the Atlantic, launch strikes against targets such as airbases at ranges that would leave little room for aircraft hosted there to scramble. This would create a “flaming datum” – a last known location of the submarine, which would increase the risk of destruction; consequently the range of targets that might justify risking the use of a high-value asset in this way is limited, with the most likely candidates being fifth-generation aircraft, maritime patrol aircraft bases and critical C2 nodes, the RN base at Faslane, and CNI. As a conflict progressed, aircraft might well be dispersed, making suppression more difficult, and as such the threat would be most acute in the early stages of a conflict.

In addition to high-value capabilities, Russia has developed containerised versions of missiles such as the Klub-K, which can be fired from the decks of cargo vessels, a mode of operation that could allow it to strike targets inside the UK with limited warning. Russian-flagged vessels and those that have left Russian ports are likely to be closely watched in a conflict, meaning that this kind of attack could only be attempted once (or at the commencement of fighting), but should even a fraction of vessels armed in this way strike militarily significant targets before being interdicted, this would represent a militarily useful effect for the loss of disposable assets. Finally, there is the threat from Russia’s long-range bombers, which can launch salvos of cruise missiles. Given NATO’s relative superiority in the air, such strikes would be unlikely to be repeatable, but early in a conflict would pose a risk of a strike against key sites from relatively close range.

There are also several long-term risks to be considered. Russia’s exit from the Intermediate-Range Nuclear Forces Treaty means that it can now more openly build ground-launched cruise missiles such as the SSC-8, as well as IRBMs. The launchers of such capabilities will likely be more survivable, and thus impose limits on left-of-launch solutions. Furthermore, if VLO UCAVs such as a successor to Russia’s Okhotnik or the Chinese GJ-11 become a part of their arsenal, the Russian Aerospace Forces may have an improved ability to strike targets such as air-defence radar, leading to the threat to emitting radar – currently primarily a problem at the tactical edge – becoming an issue at the operational and strategic levels. If, similarly, Russia develops a much larger intermediate-range ballistic arsenal (potentially through its increasing industrial collaboration with Iran and North Korea), the ballistic missile threat at strategic depth could become more significant.

The threat to the homeland is likely to be most potent early in a conflict, when the value of strategic surprise is highest and NATO Joint Force Air Components (JFACs) and Maritime Component Commands are being stood up. After this, high-value targets will have dispersed, and many of the approaches to the UK will be covered by assets in the maritime domain, or by allies’ air-defence networks. The most important role for GBAD in a homeland defence context will thus be early in a conflict, when it can act as a last layer of point defence for critical targets. The ability to disincentivise surprise – which could be possible if a ship or submarine slipped allied maritime nets – will be an important pillar of deterrence.

The threat to ports, APODs, fuel and munitions storage sites, and command posts in Europe beyond the homeland will likely persist over the course of a conflict. Buried targets such as command posts will primarily need to be defended against HGVs, ballistic missiles and, to a lesser extent, cruise missiles. In contrast, softer-skinned targets are more likely to be engaged with a spectrum of threats, including one-way attack UAVs. Forward bastions such as Kaliningrad could allow Russia to use shorter-range missiles such as the 9M723 or the P-800 against targets that would normally have required medium- or intermediate-range missiles. Of course, not everything can always be protected, and priorities for protection will be determined in line with a Joint Prioritised and Defended Assets List. Air defences including GBAD will likely be most important in the early phases of a conflict, when a force is deploying, and near those nodes that are both critical and which cannot be defended by passive measures such as concealment, hardening or dispersion.

In effect, then, there are two major roles for UK GBAD at the operational and strategic levels within Europe:

• Providing a last layer of point defence for critical facilities within the homeland in the very early stages of a conflict.

• Contributing to the defence of operational-level targets such as APODs, SPODs and headquarters in continental Europe for the duration of a conflict.

In an expeditionary context, shorter-range threats may have operational-strategic significance. This stems from the fact that many theatres do not have the depth that Europe possesses. Additionally, in expeditionary contexts where power projection typically depends upon a local coalition partner, the homeland of this (usually nearby) state becomes a strategic target in the way one’s own homeland would in a territorial defence context in Europe.

For example, in the Persian Gulf, UAVs, cruise missiles and ballistic missiles are all capable of striking operationally and strategically relevant targets. The diffusion of precision strike capabilities means that many of the air threats currently emerging within Europe will likely also be faced in a wider range of contexts. For instance, Iran currently fields ballistic missiles such as the Zolfaghar, which has a CEP (circular error probable) of 10 metres, and the Fattah, a quasi-ballistic missile comparable to the Kinzhal. The proliferation of commercially available satellite imagery can, moreover, make the surveillance of fixed infrastructure and well-known chokepoints with relatively low data latency viable for a range of opponents, and not just peers. Finally, in geographically constrained theatres, comparatively cheap assets with a limited field of view (for example UAVs such as the Chinese-made Wing Loong) can also be used for surveillance and battle damage assessment near fixed infrastructure, enabling more responsive targeting.

Having described the threat environment, we now turn to the question of the tools with which defenders can contend with the range of threats they will face, and the ways in which these tools can be integrated.

II. Surveying the Tools of the Defence

The preceding survey of the threat landscape that the UK’s IAMD must be able to contend with highlights some of the characteristics that are necessary for an effective defence. The spectrum of threats described necessitates a shift away from functional localisation – in which each system performs a defined task – towards a more distributed approach. In the latter context, effectiveness is determined at the system level, rather than through the platform-level metrics that presently characterise IAMD (such as the distance at which a target is detected, the number of shots possible, and missile Pk).

This shift in focus implies the following sub-criteria for effectiveness:

• Because the sensors needed to classify the full spectrum of threats cannot be held at all echelons, British IAMD must be able to assign or leverage a range of British and allied systems (some of them not purpose-built for air defence) to detect, classify and track threats.

• British IAMD must also be able to assign the best positioned and most economical effector to engage a given threat.

• The IAMD architecture must not be premised upon single points of failure.

• To meet evolving threats, the defensive architecture must be able to incorporate new sensors and effectors as these are iteratively developed.

Within this context, British Army GBAD will need to be designed around the following criteria:

• Army GBAD must be able to both draw on and contribute to a joint and Alliance-level recognised air picture that enables assets organic to manoeuvre formations to leverage data from higher echelons (and vice versa).

• Since the army will not immediately own the range of effectors needed to intercept the full spectrum of threats, it must be able to contribute to a joint and allied defensive counter-air effort by reinforcing system-level effectiveness. It can do so by optimising against converging lower-tier threats, thus allowing other platforms to optimise against elements of the threat spectrum that still require bespoke solutions (such as ballistic missiles or HGVs). It can also accomplish this by reinforcing the resilience and agility of the overall C2 architecture.

• Since new capabilities may be fielded, the army’s GBAD system must be sufficiently flexible to integrate systems it was not originally designed to incorporate.

To assess how best to integrate the various components, it is first necessary to consider the sensors and effectors most relevant to engaging the identified threats. This too must be broken into tactical and operational-strategic targets, as there are different assumptions that can be made about the availability of power and the distances involved, which alter the available sensors.

Tactical Defensive Systems and Capabilities

Defensive systems can be categorised in line with the threats that they counter, each of which presents different requirements:

• Low-level threats.
• Medium-level threats.
• High-level threats.

Low-level threats comprise tactical aviation, loitering munitions, cruise missiles and low-flying aircraft. In essence, these threats try to minimise their detectability and therefore targetability by using the curvature of the Earth and terrain masking as they approach their targets. The targeting methodology for countering these threats must be based upon detection and tracking over as great a distance as possible to understand their route before moving appropriate assets into position to interdict them. A system of mutually reinforcing methods of detection to enable this might be comprised of four layers, as described below.

Firstly, the force would benefit from early warning left of launch through national technical means. Understanding that a strike sortie is being prepared from an airbase, or that orders have been distributed to fire a loitering munition salvo in depth – whether through satellite imagery or signals intelligence (SIGINT) – allows the alert status of relevant systems to be brought into readiness. For example, US Northern Command expects to fuse data from multiple sources to detect preparations for ballistic missile launches several days in advance. If air defence assets are likely to have to move to be in position to achieve an intercept, early warning allows these mobile groups to prepare to move once an axis has been identified. This will be easier to achieve against some threat types, such as air-launched cruise missiles such as the Kh-101, which are launched from strategic bombers. While it is possible to track the launch platforms of submarine- and ground-launched cruise missiles, these are comparatively elusive. Even here, however, national technical means – particularly in areas like SIGINT – will be invaluable. The challenge is to distribute information to deployed GBAD headquarters at the appropriate classification, since Above Secret traffic is often hard to move forward.

Secondly, a sensor picket needs to have sufficient coverage to be able to detect and track threats as they approach their targets. Tactical echelons can draw on sensors likely to be held at the corps level or by other services. For example, an AN/TPY-2 radar organic to the THAAD system can spot relatively low-radar cross-section objects above 10,000 feet over a wide area at ranges of 250 km. The THAAD system is likely to be held at theatre level (or at the corps echelon at the very lowest), and operated by allies, but can provide critical early warning to tactical air defences. Airborne or elevated payloads able to provide track data to an effector can considerably expand a system’s reach without exposing operators on the ground. Such a sensor might be mounted on a balloon, a UAV, a helicopter or a mast. This class of sensor also includes airborne sensors such as the AN/APG-81 radar on the F-35, which are capable of effective discrimination against low-profile targets. Crucially, not all these sensors will be controlled by the Land Component Command, but their data, when available, will be important for target discrimination. The purpose of such a system would be to enable higher-end munitions to have track-quality data against low-flying targets such as helicopters and cruise missiles if they evaded the laydown of effectors on their anticipated flight path, and where the defensive system is not sitting as point defence for the intended target. This kind of integrated sensor picture should become easier to maintain as AESA radar proliferate, providing multifunctional payloads. Although such a multifunctional radar may not provide track-quality data, improved analytical tools are increasingly able to turn sub-track-quality data into a sufficiently reliable track to guide an intercept.

The third layer of situational awareness is drawn from sensors held by the tactical formations with which GBAD systems will operate and which they will protect. Since system-level effectiveness requires leveraging multiple types of data, GBAD can often benefit from drawing on sensors which are part of other formations, particularly when operators wish to avoid unmasking. These sensors include spectrometers (able to identify loitering munitions through their control frequencies and attack aviation through communications), acoustic sensors (able to detect the engine sound of low-flying objects), and passive coherent locating radar. There are a wide range of uses for these kinds of sensors. Spectrometers will be held by EW troops, while acoustic sensors can be used by artillery for counterbattery fire, and by manoeuvre elements for identifying enemy firing positions; if mounted on vehicles, they can also be distributed across the depth of a defence to provide updated tracks on munitions such as cruise missiles. Passive coherent location is more specialised, but is likely to become significantly more widespread, because of the requirement for units to self-protect from uncrewed aerial systems (UAS), while avoiding detection via direction-finding methods that can allow their positions to be inferred based on the signals they emit. The question is whether the detections from these sensors can be provided to the air defence system to offer a track for low-flying targets. This track is not sufficient to guide effectors, but is likely sufficient to accurately predict course and speed, and to cue other sensors.

The final component of the system may be understood as the sensors directly linked to effectors on the platforms attempting to achieve an intercept. An obvious example would be the Giraffe radar organic to a system such as Sky Sabre. In the case of UAVs, heavy machine guns on remote weapon stations should be able to slew to engage if appropriately programmed, using their electro-optical sensors; the trick would be to place these effectors on the flight path identified. In the case of MANPADS, which can be an economical means of engaging more capable UAVs and engaging cruise missiles, the electro-optical clue is sufficient. For aviation, high velocity missiles and lightweight multirole missiles are both viable munitions, as are 40-mm CTC cannon and other systems, provided the platform is aligned to anticipate the threat. This is easier said than done, however. In many instances, threats such as cruise missiles will be programmed to use flight paths that use terrain masking, and which allow them to approach their targets on circuitous routes, reducing warning times and confounding efforts to align platforms with threat vectors, thus reinforcing the importance of leveraging data from offboard sources.

Medium- and high-level threats comprising ballistic missiles and VLO aircraft (among others) will depend on a similar sensor architecture. The primary difference is that defending against these targets will impose a greater reliance on bespoke, rather than general, solutions. (Consideration of the threat from ballistic missiles is similar to the defence of operational-strategic assets, and so will be covered in the next section.)

Regarding VLO aircraft, different VLO implementations will have different exposure. The challenge lies in understanding the unique signature of these platforms, and in sifting that signature from the noise. One of the hardest things for an aircraft to mitigate, however, is its visual signature against the sky, such that image-recognition algorithms and electro-optical sensors can be paired to pick out VLO aircraft. Even so, the visibility of these aircraft does not necessarily mean that a missile can acquire a target: it may require beam riding or other solutions to enable an electro-optical camera to guide the munition.

In addition to a layered architecture for detection and classification, an IAMD system needs an appropriate mix of effectors. This mix includes: short-range solutions with high performance to defeat fast targets such as cruise missiles; short-range solutions with low performance to defeat threats such as loitering munitions; medium-range solutions able to close down approach axes to aviation and fast air; and long-range solutions that are able to defeat aircraft at high altitude, as well as providing point and area defence against tactical ballistic missiles.

The British Army is unlikely to own the full spectrum of effectors, given the current budgetary allocation for GBAD. Many effectors relevant to tasks such as long-range air defence and BMD (Patriot, for instance) will be operated by allies. In terms of command relationships, medium- and upper-tier air defence systems will often fall under the control of the air and missile defence commander within the JFAC who exercises control over maritime platforms capable of BMD. This means that the army will also need to plan around the eventuality that some of the systems that it owns are not always protecting manoeuvre formations.

However, even when the British Army does not control allied and joint assets, the ability to draw data from them will be critical to performing many air defence functions, especially when the full spectrum of interceptors is not available because the air defence commander has tasked them elsewhere. As illustrated by the Iranian attacks on Al-Asad and Erbil, where early warning from the US’s Space-Based Infrared System and the Turkish-based AN/TPY-2 radar gave unprotected US forces time to take cover, an integrated system creates avenues to pursue reversionary mechanisms when resources are scarce.

Furthermore, land sensors can provide early warning and occasionally track to other systems under the JFAC. The G-AMB radar on Sky Sabre, for example, can provide data on an overflying cruise missile to an offshore destroyer to enable a remote engagement (interceptor ranges typically exceed sensor ranges). As such, those air defence capabilities that are organic to British ground formations and nearby allied forces can produce data for the theatre commander, rather than just ingesting it. In contexts where the British Army is providing a C2 structure for an allied ground force in a given part of a theatre, this necessitates the ability to both ingest data from British and allied assets and to pass it to the JFAC in a timely manner.

Defensive Systems and Capabilities at the Operational and Strategic Levels

A similar layered sensor architecture is likely to be needed at the operational and strategic levels. Where possible, launch platforms will be identified by national technical means, while maintaining tracks on manoeuvring targets over a wide theatre will necessitate a reliance on offboard sources, including air-based systems. The primary differences between systems relevant to threats to targets in tactical and operational depth is that the latter requires tracking fast-moving targets such as ballistic missiles, which necessitates a greater reliance on dedicated radar, typically operating between the S-band and the X-band. The high speed of targets like ballistic missiles and HGVs makes the rapid acquisition of track-quality data a priority. Thus, the sensors relevant to this part of the detection and classification cycles must be activated and cued as quickly as possible. This, coupled with the relatively low risk of suppression at depth, incentivises a greater reliance on active radar organic to a system. That said, non-radar-based sensors will still be needed for tasks such as discriminating targets from decoys in their terminal phase.

The type of UK GBAD equipment likely to be procured under the current equipment plan will not have the organic sensors needed to track many of the threats the UK will face, and the interceptors to deal with several classes of threat will also be lacking. For example, under current plans, the UK will have no ground-based BMD or counter-hypersonic capability, creating a capability gap which will need to be addressed as part of a wider IAMD strategy. Under present assumptions, the land-based component of UK IAMD will only be functional at the operational and strategic levels of warfare, in tandem with joint force and allied assets. This is not to say that UK GBAD cannot play an important supporting role, however.

As discussed in previous sections, cruise missiles constitute the primary threat at the strategic level. Assuming that the RN is able to provide at least one Type 45 (or, in the future, Type 83) destroyer for BMD missions, the army and the RAF can facilitate the RN’s limited VLS capacity being allocated to BMD by respectively providing point and area defence against cruise missiles. The RAF, which can respond across a wide area with its Typhoon aircraft, is best suited to area defence, while army MRAD and SHORAD can provide point defence for key nodes. If the threat evolves to include a larger number of adversary IRBMs or a limited number of conventionally armed HGVs, there may be a case for a national BMD or counter-hypersonic capability equivalent to Arrow-3 (which Germany has purchased for this role). Given the difficulties inherent in developing a domestic solution, this would mean a potential requirement to integrate new (and likely non-UK) capabilities.

It is worth noting that the Land GBAD programme could have a disproportionate cognitive impact on enemy planning for operational and strategic strikes. If, for example, the enemy assesses that key RAF bases are undefended, then the risk/reward calculus in conducting a small-scale raid with long-range bombers may appear more attractive. Although the strike platform could be lost, the probability of effect on target if the missiles were launched would be high. If, by contrast, the enemy must plan on the basis of GBAD providing point defence to these facilities, then the size of sortie that must be generated to be confident of achieving an effect alters the risk/reward calculus. Moreover, the inability to determine which munitions would succeed in striking which targets – even as part of a large salvo – would make the impact on the target unpredictable. In this way, relatively small investments in GBAD have the potential to significantly alter how attractive targets in the UK appear to the enemy.

At the operational level within Europe, as well as on expeditionary missions, the threat environment will be more complex, comprising SRBMs, cruise missiles, loitering munitions and fixed-wing threats. In these contexts, in addition to providing sensors and effectors against certain threat types, the British Army can add greatest value to what is likely to be an Allied or coalition system by reinforcing that system’s capacity to coordinate its disparate elements and to retain its coherence in the face of disruption. In terms of effectors, it is worth noting that Sky Sabre is particularly well-suited to being assigned intercepts of cruise missiles targeting key sites, and this layer of defence is something the British Army can offer to allies. The key requirements for UK GBAD at the operational/strategic levels are:

• Providing a data fusion node and reversionary C2 mechanism to coordinate sensors and effectors that reside under the joint force or allied control.

• Countering the lower-tier elements of the threat spectrum to allow other assets to optimise against upper-tier threats.

A similar classification of target types – high-, medium- and low-altitude – can be adopted to that used at the tactical level, with the caveat that at the operational/strategic level, targets such as HGVs will blur distinctions. The balance of relatively bespoke sensors needed to track many operational threats means that they will be national or Alliance assets. Moreover, planned ground-based platforms will not, for the foreseeable future, carry hit-to-kill interceptors, meaning that the UK’s BMD capability will be primarily maritime. Effectors that can be used in counter-hypersonics, such as glide phase interceptors, are also not currently envisioned, and will likely be held by allies (and potentially by the RN).

In terms of C2, key capabilities at the operational/strategic level will likely fall under a NATO Air Component Command (ACC). This could be true for Sky Sabre, if authority over it is transferred to the NATO C2 structure, but also for lower-tier capabilities that may be required to act as “gate guardians” protecting long-range air and missile defence systems from low-flying threats – such as UAVs that underfly their radar. The UK has insufficient Sky Sabre systems at present, and would face severe overstretch in trying to protect a combination of UK sites, deployed forces and NATO. In exercises, the assumption is often that UK Sky Sabre would be under divisional command. This is not a sound planning assumption.

While in many instances, British land forces will not directly command joint and allied assets, they can reinforce the resilience of joint and allied C2. The allied C2 nodes that provide overall coherence will likely be targeted and may be struck; to degrade gracefully, a system must have nodes which can control locally adjacent assets in the absence of higher-level C2, and coordinate with other similarly situated command capabilities if needed. This requires the existence of reversionary command posts, and for the bearers to transfer data to and from them. For example, in the context of the Russian integrated air defence system, battalion-level data fusion and C2 nodes such as the D4M1 Polyana and the 55K6E can allow both the coordination of assets and the fusion of data even if higher-echelon command posts are knocked out. Developments in areas such as software-defined signal processing, illustrated by programmes such as DARPA’s (Defense Advanced Research Projects Agency) Dynamo, show the ways in which improvements in processing power will make networking across waveforms easier over time. The US Army’s Integrated Battle Command System has coordinated multiple disparate assets at its engagement operations centres, routing data either through gateways or through third-party platforms that can receive certain waveforms and retransmit them at compatible frequencies.

Even if the army C2 construct supporting air defence does not own many of the most relevant sensors and effectors, it should be able to reinforce the resilience of an allied or coalition system by coordinating elements of an operational-level defence over a given sector of a theatre (within Europe) or the entirety of a smaller theatre (at reach) on a reversionary basis.

In addition to reversionary C2, the British Army should be capable of contributing to a shared recognised air picture at army deep and beyond. In the context of cruise missile defence, the army can do this with its own sensors; when forward deployed with manoeuvre formations, these sensors can feed data back about targets – such as cruise missiles which overfly them. In the context of BMD missions, the army’s lack of BMD-capable radar can be offset by a C2 architecture that allows it to incorporate data from BMD-capable allied tactical assets (such as the G/ATOR), enabling it to relay this information to higher echelons when it is needed without their being overwhelmed by data.

Since it is uneconomical in terms of data management to have these platforms feeding into CAOCs or maritime air operations centres on a persistent basis, one way for their utility to be leveraged when they are needed for IAMD is for the GBAD C2 architecture to mediate data flows. As such, both BMD and counter-hypersonics require that UK GBAD C2 must be capable of distributing relevant data to higher echelons on a time-sensitive basis. It may also become necessary to share data with national civil defence authorities (much as the Israel Defense Forces do with Israel’s Home Front Command), especially if not every inch of national soil can be defended. In undefended areas, air defence can still contribute to warning mechanisms, as in the app-based systems used in Israel and Ukraine.

Finally, army air defences can optimise for point defence against cruise missiles, aircraft and loitering munitions. This will be important both to allow other joint and allied force elements to optimise against upper-tier threats, and to defend the very systems that enable tasks like BMD (since many defensive systems optimised for higher-tier threats are themselves vulnerable to low-flying ones). Consider, for example, a 2017 incident in which a North Korean UAV was found crashed near South Korea’s THAAD site, having flown there unobserved. Several types of sensor may be relevant to this function. First, radar can be combined with methods of detection such as electro-optical and IR sensors. These sensors can usefully aid discrimination against targets that carry countermeasures optimised to defeat radar. Secondly, and as at the tactical level, elevated radar can considerably expand coverage and thus system alertness (the British Army holds several G-AMB radar, unattached to Sky Sabre batteries, that could contribute to this role). While radar suppression at depth is relatively unlikely, the fact that it may become more likely could also incentivise drawing on sources such as civilian radar to complicate the task of suppression and limit the time for which a dedicated military radar must emit.

The range of capabilities needed to contend with a complex threat environment makes their effective coordination a complex organisational and systems-engineering task. It is to the question of how this task might be accomplished that the paper now turns.

III. Requirements for Land GBAD C2

Having considered the span of threats that a future Land GBAD C2 architecture must be able to manage, and the breadth of sensors and effectors that tackling these threats may need to draw upon, it becomes possible to outline some characteristics of a future-proof C2 architecture. This chapter outlines these requirements, both in terms of the systems the C2 architecture must integrate, and where decision-making is located.

Moving Beyond Integral C2 Relationships

The British Army is fundamentally an expeditionary force, and this is critical to its utility to the British state. By offering partners and allies reinforcement, the British military allows threats to be contested at reach. The challenges of force projection mean that the British military often finds itself deployed without all its equipment, and that the exact timeline on equipment availability is shaped by the distance at which it is projected and the available infrastructure. Furthermore, while land forces may provide a key contribution in some theatres, the capabilities relevant to tasks such as defence against tactical ballistic missiles may be maritime, or a partner capability. The key point is that when the UK fights, it necessarily does so as a joint and multinational force – and this is especially true in the context of air defence.

As well as having an expeditionary character, the British military is also becoming more dependent upon – and integrated with – its partners and allies. During the First World War, Lord Kitchener directly instructed that the British Expeditionary Force was to remain under independent command, such that deconfliction with French and Belgian forces was largely achieved through the allocation of battlespace. Processes have moved on since then, and NATO C2 has long functioned on the presumption of combined air operations, multinational joint effects, and Alliance-level planning. Nonetheless, C2 has – historically – been simplified by echelons and battlespace being divided between countries. This approach has made sense, since different echelons operating fixed areas of interest could be determined by the range limitations of their sensors and effectors. Today, however, all echelons can reach and strike into operational depth, while all echelons also have access to ISR into strategic depth. In a context where effects from all echelons can be applied across one another’s boundaries, battlespace management has thus become more complicated.

The criticality of being able to integrate or at a minimum interoperate with allied systems is further demonstrated by the implications of a protracted conflict. It is possible, for example, that a high-performance system with limited interoperability could offer a tactical advantage early in a conflict. But experience in Ukraine has demonstrated that as a war becomes more protracted, new systems are developed, and that dependencies on allies change as stockpiles, production rates and rationalisation change both what is available and what is produced. This dynamic may even extend to adapting air-to-air munitions to fire from the ground, or using air-to-ground munitions to fire against air targets. It follows, then, that the C2 system must be able to continue working with sensors and effectors, even as the assets assigned to the system change over time and are adapted to meet demand.

Even a cursory examination of the sensors outlined in the previous chapter demonstrates that some of them are exquisite air defence assets (and likely permanently under the control of the air defence formation). The majority of sensors are, however, primarily tasked against other problem sets. A vehicle’s acoustic sensors, for example, are placed on the combat vehicle to detect enemy vehicle movement and origin of shot; that these sensors can provide a screen to detect enemy UAS is invaluable, but only if the C2 system can enable data to be moved to the relevant effector. Another element of the challenge is that against a low-flying threat such as a cruise missile, a passive radar on a C-UAS system forward may be able to track the munition for as much as 60 km of its flight, even while a higher-echelon air defence radar is prevented from doing so by terrain or by system characteristics – and yet it may be the higher echelon system that has the effector. Whether the track data can be passed from the forward sensor and refined sufficiently to provide a guidance solution is dependent upon latency and on the compatibility of data between systems.

Similarly, effectors may be held either by the air defence organisation organic to a manoeuvre formation or by an ACC. In addition to dedicated effectors, there is also a plethora of non-dedicated systems such as jammers, multispectral smoke and DRFM (digital radio frequency memory) decoys, which will not be under the direct control of the air defence organisations at any level, but which can nevertheless contribute to air defence. Coordination with these capabilities will be critical to ensure deconfliction and the economisation of interceptor expenditure.

As the battlefield is increasingly flooded with sensors, many mounted on uncrewed platforms, opportunities will emerge for 7 Air Defence Group to reach beyond its own capabilities. However, the battlespace will also become more cluttered, particularly at the FLOT, as more elements of the force employ UAS. Indeed, UAS are destined to become ubiquitous at all echelons in the British Army, and the tactical context of their employment means that most UAS flights will not be cleared with the CAOC or planned in accordance with the air tasking order (ATO). In Ukraine, a significant proportion of higher-echelon UAS losses derive from friendly fire (for Russian and Ukrainian forces alike). Nor is it necessarily viable to have IFF (Identification Friend or Foe) as a widespread capability on UAS, both because they are likely to be captured in significant numbers, creating opportunities for the adversary to pass themselves off as friendly, but also because of the price-point dynamics on most UAS platforms.

For the UK, the central point is that Strategic Command must exercise influence over C2 for the Land GBAD programme to ensure that it is compatible with developments within the army and across the other services, and critically that the UK’s Multi-Domain Integrated Systems programme addresses the problem of blue-force tracking in the context of expanded UAS and C-UAS coverage across the battlefield. The risk of fratricide in an environment saturated with aerial objects is real, and is amplified as air defence elements become required Tom Keatinge is the Director of the Centre for Finance and Security at RUSI.tooperate in isolation. During the invasion of Iraq in 2003, for example, isolated Patriot batteries – lacking wider situational awareness – were responsible for shootdowns of friendly aircraft. Brokering situational awareness to minimise the risk of misclassification of targets will be a major task for air defenders.

In the light of these requirements, an effective fire-control C2 architecture must be able to manage three kinds of data relationship:

• Integral.
• Habitual.
• Incidental.

Integral relationships can be thought of as the fixed, low-latency C2 links between air defence assets held under organic command by the headquarters. This is the type of relationship with which air defence operators across the force are currently most familiar.

Habitual links, meanwhile, constitute air defence assets whose primary responsibility is the point defence or force protection of other elements of the force. These elements would usually be subordinated to the unit they are supporting, but they would benefit from the common air picture, and sometimes may also benefit from warnings provided by higher-echelon sensors under the control of the air defence headquarters. On occasion, however, these assets’ sensors may be critical to a successful air defence engagement overflying their area of responsibility, or their effectors may need to be moved to put them in position to intercept a threat against higher echelons. These units, therefore, must become habituated to having their systems periodically connected to the air defence C2 architecture, with as low a latency as possible. An obvious example would be the relationship between air defences afloat and those ashore – a relationship that should also extend to GBAD. In an Alliance context where UK GBAD platforms find themselves reallocated alongside Allied systems to support the assessed main line of effort, habitual relationships with Allied platforms will emerge, such as between Sky Sabre and Polish SA-6 systems.

Incidental links differ from the other two categories because they comprise those units that are not primarily responsible for air defence, but which may become reliant on the air defence command for the purposes of synchronising and timing their countermeasures, or because they have incidentally collected information relevant to air defence and are seeking to share it with the headquarters. Latency requirements in this context may be more relaxed. Bearers are almost certainly non-bespoke and are used by many parts of the force, but there must be a means for priority information to be routed appropriately when these situations arise. An obvious example of such a relationship would be with the sensors of aircraft that share the battlespace with GBAD systems. The incidental relationship can also run the other way, with data from air defence radar being used to extrapolate launcher locations and thus enable suppression by artillery or an over-the-horizon aircraft, for example. This approach is central to both Israeli concepts of operations and to South Korea’s “Kill Chain” system of IAMD and strike assets. While some radar are explicitly designed to determine launch points, even those that are not can narrow the search parameters for other sensors if they can track enough of a missile’s trajectory.

The Technical Demands of Context-Driven C2

There are three organisational/technical barriers that must be overcome if British GBAD is to manage the requisite range of relationships. First, data must be passed across alliances and coalition partners which operate a range of systems. In the context of maritime BMD, data sharing between allied systems has proven to be a considerable (but not insurmountable) systems-engineering challenge, a point illustrated over the course of multiple iterations of Exercise Formidable Shield. National caveats are also a concern. One example of these (albeit not from the world of IAMD) is that in the past it has been difficult for allied assets to plug in to a US carrier battlegroup because SIPRNet was a no-foreign-nationals network; even when this ceased to be the case, foreign access remained tightly controlled. Classification boundaries will also need to be surmounted within the joint force if data from sources such as the F-35 is to be leveraged. Alongside the challenge of processing data, a GBAD system will need to move and receive data across heterogeneous networks, where the available bearer is dependent on the line of effort that it is supporting.

A final challenge that will need to be overcome is the likelihood of capability growth that cannot be perfectly anticipated. For example, the army might invest in an upper-tier defensive system if the task of BMD becomes too much of a drain on RN resources, or it might incorporate directed-energy weapons into its SHORAD architecture. Critically, if SHORAD solutions against C-UAS become highly effective, the demand for UAS to be fitted with IFF will increase, thus expanding the need for C2 over these capabilities. A C2 system’s effectiveness will be determined by its capacity for iterative adaptation such that it can incorporate new sensors, effectors and processes. One of the great successes of the Aegis system, for example, is that its design process presumed that the system would prioritise the capacity for iterative change as new baselines were introduced, even if this meant setting initially conservative goals in capability terms.

Based on these three challenges, the following design principles for army C2 for air defence assets can be derived:

First, the system must be capable of translating data across formats at pace. The heterogeneity of the systems operated by allies and coalition partners with which the air defence network must integrate, as well as the need to draw data from a range of sources within the joint force, makes this a sine qua non. In coalition contexts, the heterogeneity of systems will be even more significant, as potential partners such as the UAE operate the Korean L-SAM and the Russian Pantsir. It is also important to emphasise the importance of being able to fuse the feeds from sources that are incidentally related to air defence with organic sensors and effectors. For example, if the effector that is most likely to intercept a target is an organic one, but the rough track data is being provided by a joint asset, while precise track data is being enabled by lining up sensors along the vector of threat, then data from several sources needs to be fused to provide a target solution to the effector.

Since coordination in capability development across the joint force and allies is unlikely, it follows that the system must depend on backwards integration. This necessitates an architecture that can be regularly updated with middleware to provide additional translation layers as required. As an example, we might think of how software such as BMD Flex was designed to connect Aegis and non-Aegis systems afloat. Another example could be the recent tests by the US Army at its White Sands Range, which connected Patriot with both F-35s and a range of bespoke systems from beyond the army. The hardware requirements that this approach introduces in areas such as processing power will create requirements for thermal and electromagnetic shielding.

Secondly, the data processing architecture of the system must be able to receive data without access to the commercially and militarily sensitive underlying source codes that underpin a given system and its architecture. Without this ability, it will be largely impossible to receive data across coalitions, given likely sensitivities about data exposure, and this may even create impediments within an Alliance context. To the extent that partners can share messages without foundational knowledge, this will be easier. This logic underpins publish/subscribe models in the commercial world, where an enterprise integration bus facilitates the translation of data across formats and acts as a messaging broker. Such systems rely on each publisher placing its raw data (messages) within a shared environment from which they can be translated and pushed on to hosted subscriber platforms. This model requires minimal compatibility in terms of data structuring, and is generally flexible in terms of the specific language types that can be incorporated. Because messaging is brokered through a central data environment, it does not require subscribers or publishers to receive data from one another directly – simplifying the systems engineering challenge that emerges from the addition of new system nodes (sometimes referred to as the N-squared challenge) because platforms do not need to “talk” directly to each other. The use of a central data environment also means that specific coalition partners do not share information directly (an issue that can sometimes prove politically challenging). Examples where this kind of integration already exists include the US military’s universal C2 interface. Any system will also need mechanisms for moving data across classifications within the joint force (for example, the US tests linking F-35s to Patriot were facilitated by an Einstein box on a U-2 Dragon Lady aircraft).

The network architecture for air defence must be a heterogeneous one, since the fusion of sensor data and the distribution of a common air picture to units not habitually part of the air defence structure will have to rely on the bearers they already possess, rather than on bespoke bearers. Even for those systems that have habitual but not integral relationships with one another, the fact that a defensive system’s deployment will partly be determined by the forces it is supporting means that the operators of these systems cannot control precisely what bearers may be available at a given time to route information to the air defence headquarters.

Several solutions are possible. The most obvious would be a software-defined system that can incorporate multiple waveform cards at a central node. However, other palliatives might be more appropriate. Data can be routed to a common node via third-party platforms that receive and retransmit waveforms. This will be especially important when the sensitivity of a network such as MADL (Multifunction Advanced Data Link) means that not every system can have a receiving terminal. Software-defined signal processing might be another way of allowing a system to receive data across multiple waveforms without a requirement for an unmanageable number of waveform cards.

Latency requirements present another challenge: when a habitual connection is taken under command by either the air commander or the headquarters of a formation-level air defence, that connection must take priority on the bearer of opportunity it adopts. The disruption this could cause makes it important that the air defence command exercises restraint and maturity over when it asserts this need for priority, otherwise commanders will likely seek to shield their comms from being available to the air defence headquarters.

Organisational Requirements for the Command Team

So far, this paper has focused on the system being commanded and how its multiple components must be able to interact. The future threat environment, however, also imposes constraints on the size, disposition and structure of the command team that must operate the GBAD C2 system, and it is important to capture these requirements.

Firstly, there are a series of vital nodes that the GBAD enterprise must be able to liaise with and draw data from. This is most realistically achieved through established data links, but also through liaison cells with terminals that can replicate the air defence command’s displays and from which data can also be inputted. The relevant points of presence across the force are likely to be:

• The Joint Effects cell in the divisional headquarters responsible for planning and controlling divisional fires. In some instances, destroying enemy strike systems on the ground may be a better means of sanitising airspace, and so the air defence organisation may cooperate on triangulating the location of threat systems. There is also the need to be notified of UAS orbits and EW plans.

• The Allied Rapid Reaction Corps (ARRC) headquarters, and its J5 and J3 fires elements, to ensure that the air defence laydown protects points critical to the corps, and to avoid fratricide, in terms of both air defence engagements and route planning. It is notable, for example, that the defensive plan for 1 German Corps in 1988 Federal Republic of Germany war plans saw the corps logistics area accidentally co-located with the Luftwaffe’s hawk batteries, due to a failure to compare the schemes of manoeuvre between these respective formations.

• The CAOC where the ATO is generated must be a priority liaison, both to ensure that blue forces are accurately tracked and to benefit from the vast ISR capacity within the air operations enterprise.

• The commander of the Maritime Component Command, both to benefit from maritime ISR, and because the UK’s BMD capability both for forces at the edge and targets at depth will be, for now at least, at sea.

• 1 Aviation Brigade, as an organisation that will be generating sorties in support of land forces and controlling air-launched effects, must also be closely tied into the enterprise. Defence of aviation assets on the ground also creates a key responsibility for GBAD units.

• Representation in the G5 and G3 shops of the divisional headquarters is critical, so that the distribution and laydown of air defence assets can be planned and deconflicted, and be complementary to the divisional scheme of manoeuvre. It also allows the enterprise to plan the resupply and sustainment of air defence units.

• Allied formations and air defence units also require liaison personnel to share a common understanding of the environment and to deconflict or coordinate engagement where effector or sensor coverage overlaps. In NATO this can be formalised, but in the Middle East or other operating environments liaison may have to be ad hoc.

• There is also a range of sensors built into civilian infrastructure (and operated by civilian agencies) in a number of states where the UK might operate, which could provide critical situational awareness and which would require liaison.

The UK’s GBAD C2 structures have, historically, met the following obligations:

• The capacity to provide a corps-level command element subordinate to HQ ARRC air branch.

• A divisional air defence command formed around one of the air defence regiments.

• A brigade-level air defence cell.

• Liaison with national air defence C2.

If the C2 of army GBAD is to expand its span of control to provide a wrap for joint and allied capabilities, there is an inherent challenge: the regular force, as it currently exists (12th and 16th Regiments of the Royal Artillery within 7 Air Defence Group) is too small to staff all the liaison functions outlined above. Moreover, air defence officers in the British military are largely generalists, on account of the career structure within the Royal Artillery, whereas the expertise needed to understand partner C2 systems sufficiently to function as an effective liaison requires extensive specialist knowledge and experience. A critical requirement for robust C2 of future GBAD, therefore, is a career structure that can produce staff with the relevant experience and expertise. The expanded responsibility of UK air defence is not simply an army aspiration, or gold plating, but a UK obligation under the country’s commitment to NATO, which includes the ARRC as a Reserve Corps headquarters. As the army is also seeking to field two divisions, the planning assumption for the staffing of 7 Air Defence Group – that it contributes to the fielding of one warfighting division – is no longer valid. The interface of GBAD with the corps echelon is also reinforced by the growing emphasis on corps operations among allies, as a result of US Multi-Domain Operations and the aspiration to leverage data from F-35 and other capabilities, which is difficult to achieve at the divisional level.

Instead, an alternative command structure might include:

• The technical basis for a corps-level command element, along with a skeleton staff that can be augmented by partners.

• A divisional-level command formed around a regiment, and brigade-level cells below it.

• The aforementioned liaison network.

There are several ways in which the headcount required to deliver these capabilities can be minimised. Firstly, automation (while not a panacea) can reduce specific burdens and extend an operator’s span of control. A formation of destroyers, for example, has six officers on watch in each destroyer, with the anti-air warfare officer supervising a team of as few as two to three personnel. This formation is expected to perform theatre air and missile defence over areas sometimes spanning hundreds of kilometres. Although this is partly a function of overall command being held elsewhere, it also reflects the fact that most modern destroyers are capable of operating on a partially or fully automated basis, meaning they can independently conduct an air defence battle over an area comparable to a corps’ – or even a field army’s – area of responsibility. While the power and processing requirements involved have historically made this more applicable to the maritime domain, where large ships could support this model, the continued miniaturisation of microprocessors is making significantly greater computational capacity deployable in distributed ISO containers.

Secondly, liaison officers to allied air defence formations and other allied formations, or to air and maritime component commands, can, if the role is professionalised, act as a force multiplier for joint planning (an analogy might be drawn with the way tactical air controllers are trained within the army). Having such individuals in post would represent an important bridge across organisations and, moreover, cycling officers through liaison roles could provide the organisational capital needed to create a skeleton air defence cell into which allied officers and liaisons from across the joint force could be plugged, if needed. A more ambitious approach to personnel interoperability might see officers from the navy and air force sit alongside army officers for training as part of a joint air defence course (as Joint Terminal Attack Controllers from the British Army and RAF do), so that they can be moved afloat or ashore as appropriate.

A complicating factor for C2 activities is that, historically, these activities would have occurred at fixed locations where the air defence headquarters could have a presence. However, owing to the threat from long-range precision fires, many of the constituent parts of the C2 system are themselves being dispersed in smaller packets. This places a premium on data transfer and compatibility between these formations’ C2 tools and the air defence system. There is also a trade-off to be made: although officers in distributed C2 nodes can gain access to the wider data sets from other similarly distributed nodes, they are unable to physically meet with other elements. The ability to ingest and dispense data becomes critical, therefore, to their utility to both the air defence command and the headquarters to which they are attached.

Conclusion

Adversaries’ expanding capacity to reach into tactical and operational depth means that air defence is now a critical enabler for ground forces, even after the establishment of air superiority. Moreover, given the number and diversity of low-cost air threats, and the competing dilemmas imposed by more capable threat systems, C2 has become the means by which an air defence system can gain the required efficiency to protect the force. This efficiency is derived from assigning appropriate effectors to the different kinds of threat being confronted.

To achieve the requisite efficiency, the C2 architecture for British GBAD must be able to distribute track-quality data to a diverse array of organic/inorganic systems and joint/combined assets. Given the increasing number of low-altitude threat systems, this track-quality data will often need to be based upon a composite track derived from numerous bespoke and contingent sensors. The collection and distribution of this data must, moreover, be bearer agnostic, reflecting the fact that partners may use an array of communications systems, and that the best-placed sensors might be embedded in units that are not organically subordinated to the air defence formation.

A further consideration is that both effectors and sensors are likely to adapt rapidly over the course of a conflict in anticipation of and response to an evolving threat. Expenditure of munitions will also invariably drive the use of increasingly irregular interceptors as a conflict protracts. The C2 architecture must therefore be adaptable, so as to be capable of interacting with new systems via software updates.

The C2 architecture itself must be distributed, both to bolster its own survivability and because it must have liaison outposts in disparate formations. Moreover, as the number of friendly UAS and effectors in the operating environment expands (many lacking synchronisation through the CAOC), the ability to access friendly planning cycles to aid with the classification of air targets is vital if the air defence system is not to engage in widespread friendly fire. Another major consideration is the mobility, signature and power requirements of the C2 system, since it risks being targeted if it has a distinct signature.

This paper has not covered C-UAS capabilities in detail, focusing instead on loitering munitions and one-way attack UAS, as these target air defences or the sites they defend. The layers of tactical UAS that are likely to become organic to all echelons, however, have not been discussed, because defence against these systems is a localised all-arms requirement, rather than something to be managed centrally. Nevertheless, one of the key ancillary questions is how the air defence network can make opportunistic use of the sensors and effectors distributed throughout the force to provide all-arms C-UAS without saturating tactical networks or hijacking a critical enabler of manoeuvre elements.

The Land GBAD programme gives the British Army an opportunity to future-proof air defence across the joint and combined force, with £1.6 billion committed to the project. But realising the programme’s goals will depend on having an open-architecture C2 capability that can integrate the increasing numbers and types of sensors that are proliferating across the battlefield.

Jack Watling is Senior Research Fellow for Land Warfare at RUSI. Jack works closely with the British military on the development of concepts of operation and assessments of the future operating environment, and conducts operational analysis of contemporary conflicts.

Sidharth Kaushal is Research Fellow for Sea Power at RUSI. His research at RUSI covers the impact of technology on maritime doctrine in the 21st century, and the role of sea power in a state’s grand strategy.