The Atlantic Bastion

The Atlantic Bastion is envisioned as a layered network of uncrewed and autonomous systems, integrated with advanced sensors and traditional manned anti-submarine warfare (ASW) assets such as the Type 26 frigate. The aim of this integrated system is to ensure that Russian undersea forces cannot pass undetected through the Norwegian Sea and the Greenland–Iceland–UK gap from the north. As it is an evolving concept, some of the assumptions underpinning this paper may be overtaken by future developments in the Atlantic Bastion programme and its associated initiatives.

This paper argues that deterring Russia by exposing it to the risk of detection alone – that is, deterrence by denial through persistent surveillance in the Norwegian Sea – is necessary but insufficient to ensure effective deterrence. The most likely Russian response would be to surge Yasen-class submarines through the Atlantic Bastion area prior to conflict, or to bypass the Bastion via under-ice transit. Either option would enable Russian nuclear-armed submarines to reach the Atlantic, compelling a US and Allied response, and diverting naval forces from the Bastion area.

Considering that Russia’s deterrence calculus is shaped largely by its perception of NATO’s ability to conduct precision strikes against key assets and infrastructure, this paper recommends that a “deterrence by punishment” element be incorporated into the Bastion concept. Specifically, the Bastion should host and protect maritime strike assets, such as cruise missile-armed platforms, to reinforce deterrence.

This paper’s central conclusion is that, despite the concept’s strengths, there is a risk that the Royal Navy defines the Atlantic Bastion too narrowly: as a network of relatively low-mobility sensors in the Norwegian Sea. Instead, the geographical scope of the Bastion should extend both westward into the Atlantic, to monitor an early Russian submarine surge; and eastward into the Barents Sea, to constrain Russia’s use of the polar front as cover for its noisier submarines. This broader conception could have significant implications for the design of enabling systems such as uncrewed surface vessels (USVs), which will require extended endurance and power capacity. It will probably add to the cost (and therefore reduce the number) of such platforms, and none of this will completely remove the requirement for continued employment of exquisite crewed systems (such as the Type 26), integrated with the Atlantic Bastion architecture.

In addition, this paper recommends incorporating long-range, non-US strike capabilities within the Bastion to make it more difficult for Russia to ignore or circumvent the system. The paper also recommends integrating naval mining and uncrewed underwater vehicle (UUV) - delivered loitering munitions into the Bastion architecture. While these strike capabilities are distinct from a purely surveillance-based Bastion concept, they would nonetheless complement its credibility as a deterrent.

In short, the paper endorses the conceptual utility of the Atlantic Bastion, but proposes expansions to the geographical boundaries of the Bastion and a mix of supporting capabilities to realise its full deterrent potential.

Introduction

This paper examines the concept of the Atlantic Bastion, as presented in the UK’s recent Strategic Defence Review (SDR), within the context of deterrent theory and the authors’ assessment of Russian risk and deterrent calculations.

▲ Figure 1: Russia’s Potential Response to the Atlantic Bastion

The Atlantic Bastion is a cornerstone of the Royal Navy’s contribution to the SDR. It is an anti-submarine warfare (ASW) barrier: a network of sensors and uncrewed and autonomous systems, supporting more traditional ASW platforms. Situated in the North Atlantic, it is intended to contribute to defence against submarine and sub-surface threats from the north, and supplement existing measures to protect the UK’s nuclear continuous at-sea deterrence. It is a defensive construct intended to protect the UK and NATO Allies, and contributes to the aim of deterring threats “so that fighting a war … is not necessary”. It is expected to be implemented gradually as equipment is procured and integrated into the network over the next few years. Precise timelines are undisclosed and will probably be dictated, in part, by the UK’s Defence Investment Plan (which remains unpublished at the time of writing).

The concept of an Atlantic Bastion is both a response to the relative scarcity of ASW-relevant capabilities at readiness within NATO, and an attempt to leverage the increasing value of low-cost uncrewed systems, which can be employed in conjunction with more expensive ones to enhance their effectiveness. The Atlantic Bastion is expected to contribute to specific strategic priorities, including:

• Constraining the freedom of action of the Russian Federation Navy’s (RFN) nuclear attack submarines. These submarines can threaten the UK’s continuous at-sea deterrence, and launch conventional or nuclear-tipped cruise missiles against the UK and NATO allies.

• Constraining the ability of Russia’s Main Directorate of Deep-Sea Research (GUGI) to conduct sabotage operations against critical maritime infrastructure in peacetime and conflict.

The purpose of this paper is to provide information that could guide the realisation of the Atlantic Bastion concept, examine its potential deterrent value, and explore some of the implications for the development of the uncrewed systems that will necessarily be developed. The report focuses specifically on the actions that the RFN – and to a lesser extent GUGI – would need to be confident of being able to take in order to play their role in a high-intensity conflict. The report does not discuss the subject of peacetime sabotage, as activity in the grey zone has a distinct logic worthy of a separate examination.

The report is divided into three parts. First, the authors examine the current deterrent value of the Atlantic Bastion, and the RFN’s best or most likely countermoves to the type of architecture envisioned. Second, the concept of the Atlantic Bastion is overlaid onto Russia’s own naval concepts and capabilities to examine the interaction between them. Finally, the authors provide an assessment of how the Atlantic Bastion concept can be fine-tuned to augment its deterrence value against Russia, and to highlight possible capability choices.

Methodology

This research is based on a qualitative review of primary and secondary literature (including Russian sources where available), and an assessment of past Russian behaviour and capabilities. It is also based on interviews with current members of the UK naval staff involved in articulating the Atlantic Bastion concept, serving and former naval practitioners in other areas, and academic subject-matter experts.

The Atlantic Bastion’s Deterrent Design

This paper describes, in geographic terms, a geometrical dilation of the Atlantic Bastion. It proposes retaining the core of the concept while making specific suggestions regarding the emplacement of specific capabilities. It also suggests a shift in relative emphasis towards conventional deterrence by punishment.

The Atlantic Bastion has the potential to support deterrence by both denial and punishment. Denial strategies “seek to deter an action by making it infeasible or unlikely to succeed, thus denying a potential aggressor confidence in attaining its objectives.” Deterrence by punishment can be described as threatening the imposition of costs (military, economic, political or other) that are large enough to outweigh the benefits of an attack.

Within the Royal Navy’s Maritime Operating Concept, the future force is described as one that will be built to prioritise (although not exclusively focus on) deterrence by denial, placing a particular emphasis on disrupting an opponent’s planning. The Atlantic Bastion would contribute to this approach, as this defensive barrier would increase the risks for Russia of deploying subsea assets against the UK, imposing planning constraints on the RFN and restricting its freedom of manoeuvre.

Deterrence by nuclear punishment is integrated with NATO planning and is the rationale for continuous at-sea deterrence, which is the “bedrock of the UK’s defence”. However, this paper argues that the ability also to deliver “punishment” through conventional means is key. It contributes to both directly deterring Russian aggression, and disrupting RFN countermoves against the Atlantic Bastion construct, in a way that reinforces the Bastion’s deterrence by denial essence. To that end, punishment, specifically conducted through conventional strike from the maritime domain, should be integral to – rather than separate from – the design of the Atlantic Bastion, and it should form a stronger part of the deterrence narrative.

The premise that underlies the Atlantic Bastion concept is that constraining the freedom of action of Russia’s subsurface assets by demonstrating the ability to detect and track them is a necessary (but not sufficient) condition for deterrence. The Russian nuclear attack submarine (SSN) fleet is growing rapidly and improving in qualitative terms, with six Yasen-class guided missile submarines (SSGNs) probably to be delivered by the end of this decade. A more scalable approach to ASW is therefore important. Project Cabot – the Royal Navy’s line of effort to deliver a credible smart barrier against Russian submarines – will build on work conducted under Project Charybdis (the Royal Navy’s related concept-development phase) and the NATO Smart ASW Barrier Initiative, to provide a UK contribution to NATO deterrence and defence. The primary output will be a barrier of surface and underwater uncrewed assets (including gliders) in the Norwegian Sea, which will initially be commercially owned and operated, before transitioning to a government-owned and operated construct. Within this layered system, uncrewed vessels and optionally crewed ones (such as the Type 92 uncrewed sloop) will be employed in conjunction with crewed assets of Allied navies, to form an overlapping barrier of sensors and effectors in the Norwegian Sea, up to the Bear Island–Norway gap.

The concept of the Atlantic Bastion (to the extent that it has been articulated in unclassified forums) must be overlaid on what the authors believe Russia may be planning for the employment of the RFN, the Russian Aerospace Forces and GUGI in a conflict with a maritime dimension. Two key conceptual considerations then emerge.

The first relates to the assumption that detection deters or at least contributes to deterrence. While there is some truth to this, the risk of detection should be considered in the context of a Russian approach that treats the dislocation of Allied platforms as a metric of success. For reasons that will be articulated in greater depth later in this paper in the section on Russian naval planning, it appears that Russia probably expects to surge SSNs in the build-up to a conflict, partially to draw naval platforms away from its own maritime periphery. In this context, the authors believe that Russia considers detection in the Norwegian Sea to be acceptable (although by no means desirable), as Russian SSNs expect to lose (or at least occupy the attention of) trackers in the Atlantic, and they have the speed to outrun most of the likely tracking platforms. This means that the Atlantic Bastion’s more robust network of sensors in the Norwegian Sea will still need to cue larger, more expensive systems that can continue trailing contacts into the Atlantic. Deterrence requires a degree of depth, which in turn imposes costs for the uncrewed systems pursued, as these will need the endurance to support crewed assets in extended tracking.

The second conceptual consideration is that the extent to which Russia commits SSNs to anti-surface warfare (ASuW) in the Bastion is directly proportionate to the NATO long-range strike capabilities within it. Although long-range strike is a separate line of effort, the ability of the Royal Navy and NATO’s European navies to present Russia with a long-range strike threat within the Bastion is key. These navies would not be displaced from the Bastion by a Russian surge (to the extent that US platforms would be drawn away to provide ASW defence to the US east coast), and will therefore influence the degree to which the RFN can choose to circumvent the Bastion in a peacetime crisis.

Russian Naval Strategy and Thinking

Predicting what action the RFN might take against the Atlantic Bastion requires reference to Russian military strategy, which differentiates between a “regional war” and a “large-scale war”. Both categories of conflict involve NATO, the distinction being intensity and geographical scope. To a certain extent, the concept of standalone Russian naval strategy is a misnomer: an independent strategic operation in the maritime domain has not existed in the Russian lexicon since the late Soviet era. Instead, the RFN operates under a number of directives on how it should support four of Russia’s strategic operations: strategic air operations; strategic operation for the destruction of critically important targets; strategic operations of the nuclear forces; and strategic operations in the theatre of military operations. The RFN’s roles in these include the following:

• executing a damage-limitation strategy at sea;

• supporting strike operations against land targets with conventional weapons;

• participating in and supporting the strategic operation of the nuclear forces by employing non-strategic nuclear weapons against targets, both at sea and on land;

• protecting and operating Russia’s nuclear ballistic missile submarines (SSBNs); and

• engaging western SSBNs, particularly in areas such as the Norwegian Sea, from where submarine-launched ballistic missiles can be launched in a way that invalidates Russia’s launch-on-warning posture.

The damage-limitation strategy should be considered, as it is related to, but distinct from, sea denial. Russia does not expect to be able to deny large tracts of the ocean to Allied navies indefinitely, and its planners recognise that the question is when and not if NATO navies will achieve relative dominance. However, the RFN and Russian Air Force can influence the time it takes Allied navies to achieve maritime dominance and the damage they incur in doing so, and may also choose to contest or challenge NATO presence and levels of sea control periodically. Since the RFN is the supporting force to the Russian army in Europe, it does not need to win; it merely to not lose for long enough for the ground forces to achieve their arms. The RFN can also support strategic goals such as war termination, through conventional and nuclear attack missions away from a front line. Strikes could target NATO command structures, support nodes, industrial capability or even centres of population, if deemed existentially necessary.

▲ Figure 2: The Russian Concept of the Maritime Domain

Spatially, the result of this strategic thinking is a four-tier rubric dividing the maritime domain into: “coastal defence zones”, “near seas”, “far seas” and the “world oceans”, as shown in Figure 2. In the coastal defence zone (roughly out to 200 km), Russia expects to maintain sea control. In the near seas zone (out to 1,000 km), it expects to establish at least temporary sea control. In the far seas zone (out to 2,000 km, where the Atlantic Bastion would be) the RFN’s primary aim is temporary sea denial. On the world oceans, Russia can strive for neither sea control nor sea denial. However, an RFN presence, particularly a subsurface one, in the world ocean could directly and immediately threaten the US or Western Europe and increase the number of dilemmas for NATO ASW capabilities. The inter-theatre mobility of naval platforms armed with sea-launched cruise missiles (SLCMs) is viewed as one of their strategic advantages.

In quantifying risk or threat, and thereby responding to NATO deterrence postures, Russian naval planners pay considerable attention to cruise-missile carrying platforms, including both surface and subsurface platforms. This is a function of their broader conceptual focus on the ability to strike operational and strategic targets at depth. Additionally, some Russian authors recognise that NATO’s ability to deploy platforms such as aircraft carriers is a function of the survivability of picket vessels such as the Arleigh Burke and Ticonderoga (or analogous Allied platforms), meaning that successful suppression of SLCM launchers and the functional defeat of aircraft carriers are effectively synonymous. NATO will therefore need to consider the potential deployment of SLCMs within the Bastion to underpin a deterrence-by-punishment effect.

Understanding What Success Looks Like

Russia’s “Best” Course of Action: Circumventing the Atlantic Bastion

In the authors’ assessment, the rational Russian response to an improvement in Allied intelligence, surveillance and reconnaissance (ISR) in the Norwegian Sea will not be to focus exclusively on directly engaging NATO assets within this far-seas zone (the area that roughly corresponds with the planned Bastion). Rather, the Russians will aim to offset the strategic threat of NATO’s maritime strike and dislocate it from areas of NATO’s choosing. In a crisis that is (potentially) escalating to conflict, this might be achieved by forcing the commitment of a disproportionate number of Allied platforms (including SSNs), towed-array equipped frigates and maritime patrol aircraft to tracking Russia’s quietest submarines in the world’s oceans. This would both draw NATO capability away from the High North, where it threatens the near seas, and diminish NATO’s maritime deep-strike capability against Russian strategic centres. Much of what has been written on naval combat by Russian senior officers stresses the importance of initiative and inter-theatre mobility. In real terms, this translates to an incentive to surge nuclear submarines and force the other side to defend, offsetting Russia’s numerical inferiority. In effect, then, the risk of detection in the Norwegian Sea may not deter the RFN from surging its SSNs, because it cannot afford not to surge them, and because SSNs will draw considerable Allied maritime and air power into the Atlantic, even if detected in transit (see Figure 1).

There are several grounds upon which the above assessment is based. First, according to the commander of NORTHCOM, Russia appears to be maintaining a near year-round presence of Yasen-class SSGNs near US coastlines. Russia currently fields a fleet of only six Yasens, with more being built. Given the need to rotate deployed capability to allow for maintenance and training, this constitutes a significant portion of the fleet committed to this role, demonstrating the considerable importance placed on having SSNs near the US East Coast. This approach mirrors Soviet activity in the Cold War, when the Akula-class submarine was routinely deployed in the Caribbean as part of a policy of “analogous response”. The USSR’s positioning of nuclear-armed cruise missiles in range of the US coastline, and therefore in range of strategic targets critical to the coordination of a NATO first strike, was a retort to the imbalance created by the positioning of a NATO nuclear-level force within Europe. Posing a direct threat to US population centres (or those of the UK/Western Europe) is a key psychological and military tactic, especially where those populations do not consider any conflict as proximate or existential.

There are two other NATO threats that Russian SSNs play an important role in helping to mitigate. The first is the challenge posed to Russia by Western SSBNs potentially being deployed close to Russia, thereby reducing warning times for a NATO missile attack. This threat is considered particularly pressing by a number of senior Russian officers. The RFN SSNs could mitigate this threat by patrolling the Norwegian Sea, making it a dangerous place for NATO SSBNs to operate and potentially deterring NATO activity in the area. The RFN will probably aim to “offset” the risk posed by allied SSBNs near Russia indirectly by operating its SSGNs close to NATO and, particularly, US territory, posing an analogous “low warning” threat to NATO. Second, the emplacement in Europe of deep strike capabilities, such as the US Army’s Dark Eagle hypersonic glide vehicle, is likely to be viewed by Russia as presenting a challenge analogous to the Pershing II. Despite being conventionally armed, prompt strike capabilities being emplaced in Europe by the US are viewed as being able to penetrate hardened targets and strategic assets that are relevant to Russia’s early warning and nuclear command and control.

Russian exercises provide an additional indication of their intent. Of particular interest is the Grom 2019 exercise, in which Russia committed all of the Northern Fleet’s attack submarines to surge operations. Several Russian commentators described the exercise as effectively being a replay of the Cold War-era Atrina exercise, in which the Soviet Navy sortied five Victor-class submarines under ice around the north of Greenland, before steaming towards Bermuda. While assessments of the effectiveness of Atrina differ significantly among former US and Soviet officers, it was clearly viewed as a success by authorities such as then Chief of Navy Admiral Chernavin (who recounted the exercise in articles written long after his retirement). One notable metric of success was the number of Allied platforms that were tied down tracking the Soviet submarines. It is worth juxtaposing US assessments of Atrina (which the US saw as a Russian failure, because RFN submarines were detected) and Soviet ones (which considered factors such as the number of Allied platforms tied down and the political impact).

The commentators drawing parallels between Atrina and more recent exercises are not policymakers. However, the comparison that multiple journalists have drawn between Grom and Atrina might be construed as (limited) evidence that emphasising the similarities between the exercises was part of the RFN’s messaging around Atrina.

A final source of evidence for the author’s assessment of Russia’s probable, rational response is that retired senior officers and academics have opined that, in the event of several quiet SSNs being sortied into the Atlantic, the majority of Allied – and particularly US – capacity would be retasked away from chokepoint defence to counter this threat. This drain on chokepoint defence would be exacerbated in a context where the Indo-Pacific, which currently absorbs 60% of US SSN capacity, receives an even larger share of a US force that will reach a projected temporary low in numbers at the end of this decade. There is operational value in a concept for ASW within the Norwegian Sea that frees up crewed platforms for the probably resource-intensive task of tracking an RFN surge. However, if the Russian aim is precisely to draw Allied assets to the area outside the Atlantic Bastion, the risk of detection in transit through the Bastion will have a limited impact on Russian planning. This will be especially true if the Russian assumption (like that of the Soviets) is that submarines will evade their pursuers further out in areas like the Sargasso Sea, where acoustic conditions become more complex because of the mixing of warm Gulf Stream water with colder water. Effective deterrence will require the ability to track contacts continuously, well beyond the Bastion itself, and the ability to limit the potential for evasion in the Sargasso Sea. Active sonar can play a useful role here, but it is difficult to employ against Russian submarines, which typically outrange Allied frigates. Uncrewed surface vessels (USVs), which can both increase sensor density and use active sonar more freely (because there is less risk to life), can therefore contribute considerably to defence and deterrence by allowing Russian submarines to know they are being watched.

The fact that Russia’s quietest SSNs are land-attack cruise-missile capable and can carry nuclear missiles will probably make them a priority for Allied (and particularly US) platforms to counter. Drawing NATO assets away from the Bastion will ease the pressure on Russia’s near-seas and far-seas zones and make it easier for the rest of the Northern Fleet to achieve sea denial there. The Yasen submarine has the vertical launch system (VLS) capacity to carry 40 3M-14 Kalibr cruise missiles, while the Akula-class submarines (such as the K-154 Tigr and K-328 Leopard) are being refitted to carry the torpedo-launched Kalibr-PL. Moreover, it is likely that Russian SSNs and SSGNs will carry nuclear-tipped missiles, as the Soviet ones did during the Cold War, when a perceived lack of strategic depth was mitigated by deploying nuclear-armed SSNs and SSBNs in the Caribbean, as already described. The assumption that, in a large-scale conflict, SSGNs will be loaded with nuclear-armed cruise missiles is supported by Russian commentators such as Konstantin Sivkov, who served on the Russian military’s General Staff for 12 years. Indeed, a nuclear capability comparable to that of the SS-N2-1 (with which Akulas were equipped during the Cold War) would seem to be the only plausible rationale for equipping the Akula with a torpedo tube-launched cruise missile, considering the small number of missiles that it could launch.

Additionally, there is a seemingly high likelihood of Borei-class SSBNs being routinely used under thick ice, increasing the number of locations within the Arctic where they can operate, and thereby partially mitigating the risk posed to them by Allied SSNs. In principle, this frees up Russian SSNs from defending their SSBNs, enabling them to instead take on more proactive or offensive roles and tasking. Exercises such as Umka 2021, in which the RFN operated three Borei-class SSBNs through 1.5 m of ice in tandem, signposted this capability and intent. A lack of under-ice currency or capability, and fewer platforms, means that NATO’s forward maritime strategy of the 1980s is no longer realistically replicable, limiting the ability to force Russia into a defensive position by threatening its SSBNs. Allied SSN capacity is likely to be limited by the demand signal for US submarines in the Pacific. Moreover, corporate knowledge regarding under-ice operations is currently low outside the US, with the Royal Navy’s last advertised Ice Exercise conducted in 2018, after a 10-year gap. A shortage of available SSNs and crews experienced in operating under ice would probably prevent NATO from tracking under-ice breakthroughs by Russian SSBNs, at least in the medium term. Although this capability could be regenerated, this would probably take some time.

Finally, a purely defensive near-seas denial approach is precluded by the RFN’s considerable defensive disadvantages, which are well understood by Russian officers. Russia’s air- and space-based ISR limitations, and less capable ASW platforms, will significantly constrain Russia’s ability to engage dynamic targets. The lack of adequate space-based surveillance stems from Russia’s failure to replace the Tselina and Legenda satellite constellations. Furthermore, Russia maintains a smaller than planned force of modernised IL-38N maritime patrol aircraft along with older Tu-142s. While the capabilities of newer ASW-capable vessels such as the Gorshkov-class frigate are unknown at this point, Russia is likely to field only a limited number of these vessels.

These factors collectively point, in the authors’ view, to the likelihood of Russia emphasising a proactive offensive posture – one that bypasses the Atlantic Bastion by surging capabilities in a crisis when engagement is less viable.

NATO’s Preconditions for Success

If part of the Russian Northern Fleet’s force of SSNs and SSGNs is likely to be surged before a conflict – either through the Greenland–Iceland–UK (GIUK) gap (exploiting peacetime maritime law and the right to innocent passage), or by bypassing the gap as Soviet submarines did for Atrina – this poses challenges to the concept of an Atlantic Bastion.

First, it interrogates the premise that the sea denial (or control) offered by the Atlantic Bastion is a valid deterrent in and of itself – even though situational awareness in the Norwegian Sea can still facilitate the tracking of Russian submarines in transit to the Atlantic (a point that will be discussed in more depth later in this paper).

The second conceptual challenge is that UK (and NATO) objectives of moving from sea denial to eventual sea control for the Atlantic Bastion area, and Russian expectations for the waters beyond its near seas, are not necessarily mutually exclusive. Effective sea control and the resultant restriction in the RFN’s (and GUGI’s) freedom of movement should, in principle, reduce their ability to threaten the UK homeland and critical national infrastructure directly. Although this objective is of key significance to the UK, it still leaves Russia other options for challenging and threatening the UK. The degree to which Russia would aspire to strike the UK directly also needs to be considered within the context of its nuclear escalation calculus. It is likely that Russia’s aspirations for these seas stop short of sea denial (during conflict), the realistic expectation being that the RFN might harass or contest NATO’s denial/control at a time and frequency of its choosing. The RFN would be unlikely to challenge maintenance of protracted sea denial. Better detection by the RFN in the Norwegian Sea is needed, as this sets the conditions for tracking contacts. However, it is not sufficient to deter the RFN if the Russian planning assumption is that detection is probable but not fatal, as submarines will surge in peacetime and lose their trackers elsewhere.

The sufficient condition for the UK’s success is therefore the ability to demonstrate that the Atlantic Bastion contributes to continuous tracking beyond the Norwegian Sea, rather than simply acting as a defensive barrier. The concept already contains elements of this sufficient condition, as multiplying the number of crewed frigates that can be spared from the Norwegian Sea contributes to this outcome. Moreover, since tracking targets over long distances is resource-intensive, there is also a case for crewed assets that can operate at reach to be augmented with uncrewed systems. This is an option that should condition the design criteria for some of the uncrewed systems used within the Bastion.

It would also be desirable to prevent the RFN from assuming that it can safely ignore what is within the Atlantic Bastion. The more compelled the RFN feels to operate SSNs within the Bastion, the greater the operational and strategic effect of the capabilities that are held within it.

Russia’s Defensive Challenge

Russian experts are specific regarding the particular NATO capabilities they regard as posing an insurmountable strategic threat to Russia from the northern vector. Chief among these are NATO’s long-range precision strike capabilities, which the Russians view as a key component of an expected “integrated massive aerospace attack”. This would involve a largescale Allied air campaign which, in Russia’s assessments, would begin with the mass employment of standoff capabilities that are, to a significant extent, maritime. Of particular concern to Russia is the prospect of conventional strike and nuclear submarine-launched ballistic missiles being used in tandem – a threat that blurs the challenges of an operational and a strategic attack. For example, in a 2023 article, the then-chief of the RFN, Admiral Yevmenov, argued that in a crisis, the number of NATO cruise-missile carrying platforms near Russian shores is likely to quadruple:

In the Norwegian and Barents Seas, it [NATO] is planned to deploy up to 50 long-range cruise missile (LRCM) carriers with a warhead of 1,000–1,100 missiles; in the Sea of Okhotsk and the Sea of Japan, as well as in adjacent ocean areas, up to 60 LRCM carriers with a warhead of 1,200 missiles; in the eastern part of the Mediterranean Sea and in the Black Sea, up to 14 carriers with a total ammunition load of 300–350 [cruise missiles]; in the North and Baltic Seas, at least 9 carriers with a total ammunition load of 180–220 [cruise missiles].

This assessment is roughly analogous to those of other Russian authors such as Konstantin Sivkov, who served for 12 years on the Russian General Staff.

As the US fields the largest NATO Navy and ASW capability, it is likely that Russian planners will need to assume that the majority of this threat will be carried on US platforms. Consequently, the ability to compel the displacement of US assets, such as SSNs and Arleigh Burkes, represents Russia’s most rational approach, as outlined above. This would be consistent with the wider logic of damage limitation in its attempts to resist a large-scale, coordinated NATO aerospace attack. Russia would probably aim to displace or remove the proximate maritime cruise missile threat, while combining its own offensive strike with its air and missile defence to collectively mitigate (if not quite eliminate) the challenge that Russia faces from NATO in the Norwegian Sea.

Russian Conditions for Success

Russian success in displacing the perceived NATO missile threat is likely to depend on two assumptions. First is that strike capabilities will primarily be held on US platforms, many of which are likely to be repositioned in the event of a surge of Russian SSNs into the Atlantic, which could threaten the US’s eastern seaboard. Second is that even after surging its Yasen submarines, Russia will have enough older SSGNs and SSNs in the Northern Fleet’s order of battle to contest the Barents and Norwegian Seas against an Allied naval force reduced by the need to reallocate resources to tracking the very submarines that Russia surged.

It must be remembered that although the Russian SSN threat is growing, it is still likely to be limited. Russia will field six Yasen-class submarines across the Northern and Pacific fleets by 2030. The Russian Federation is planning to build at least four more Yasen-class submarines. Theoretically, Sevmash has the capacity to build this order in parallel (having previously constructed five Yasen-class SSGNs in parallel), and could deliver this tranche by the mid-2030s (with progress likely to accelerate after yard capacity currently allocated to the Borei-class SSBN becomes available). In addition to older SSNs such as the improved Akula and SSGNs such as the Oscar II, this would provide the Northern Fleet with 14–18 SSN/SSGNs (depending on whether the fleet’s older Victor III and Sierra IIs are scrapped by this point). This fleet, although significant, is relatively small, and marginal losses would make it difficult to perform missions both on the world’s oceans and closer to Russian shores.

NATO Conditions for Success

For NATO to convince Russia that its capability to employ its SSNs is constrained, three preconditions must be met.

First, the Alliance requires the ability to track Russian SSGNs surged prior to any conflict on a persistent and reliable basis, even as these assets enter complex waters like the Sargasso Sea. As forward-deployed SSGNs are an integral part of Russian strategic deterrence of the US, the ability to demonstrate that these can be tracked will have a considerable strategic deterrent effect. By enabling crewed platforms to pick up a trail, the Atlantic Bastion can, in principle, achieve this aim. However, the Russians must understand that they are being tracked, and the varying institutional memory of Atrina suggests that this is not always the case.

Second, as the level of resource allocation needed to provide depth will probably strip the Norwegian Sea of crewed assets (and particularly US assets), the Russians must believe that, even if US platforms are reallocated, the Alliance has sufficient strike capacity within the Bastion to pose a credible risk. In effect, dislocation cannot be allowed to be a viable aim for the RFN. The SDR recognises littoral and maritime strike as distinct from the Atlantic Bastion concept. However, the Bastion will have a more limited impact without strike being incorporated within the Bastion area. As the two elements that Russia wishes to keep out of the Norwegian Sea are conventional strike capabilities and SSBNs, the presence of these capabilities there makes the Bastion an obstacle to be assaulted rather than circumvented.

Finally, attrition inflicted on those SSNs that the RFN holds back for ASuW in the Barents Sea and beyond can impose dilemmas on the RFN’s leadership. A demonstrable ability to engage older SSN/SSGNs will make it harder to allocate newer SSGNs to surge missions. The Bastion can usefully contribute to this.

Operationalising NATO’s Deterrence Posture Through the Atlantic Bastion

The argument articulated so far is that, the optimal Russian counter to an effective Atlantic Bastion – a peacetime surge – can be blunted by NATO if the preconditions outlined in the previous chapter are met. First, the offensive capabilities that sit within the Bastion must be sufficiently robust that Russia cannot ignore them and must task SSNs with engaging them. Second, the capability to effectively trail Russian submarines that do surge into the wider Atlantic must be robust. As will be explored below, these assumptions can guide how the Royal Navy prioritises subregions within the relatively large area that constitutes the Bastion and can also inform the generation of capabilities to augment the Atlantic Bastion.

What emerges from these assumptions in conceptual terms is the proposal to create a three-tier defensive system for NATO and the Atlantic Bastion. The first element of the system should be a screening layer in the western Barents Sea, at the polar front. It is in this part of the theatre that distributed low-mobility sensors will have greatest value, both as a redundant means of early warning (assuming a likely Russian sabotage against sensor networks like the Integrated Undersea Surveillance System (IUSS)), and as a means of limiting Russian freedom of action in the Barents Sea once a war begins. The latter role is of particular value against submarines like the Oscar class, which will be held back for ASuW.

The second component of the system should be a tracking layer capable of following those Russian SSNs that are surged deep into the Atlantic. Crewed assets can contribute to this layer, especially if freed from some functions in the Norwegian Sea. However, the resource-intensive nature of trailing a contact, and the value of alerting Russian submarines to the fact that they have been detected using active sonar, make a purely crewed approach less than optimal. Larger uncrewed systems should form part of the trailing layer, and this will shape the requirements for some uncrewed or optionally crewed systems such as the proposed Type 92.

The final layer of the system should be a shaping layer comprised of assets equipped with maritime deep strike. This layer both determines the extent to which Russian SSNs are able to ignore the Bastion, and shapes where NATO’s ASW capability must operate. NATO must allocate ASW assets to ensure the protection of strike assets from the Russian submarine threat as the RFN would probably need to attempt to engage cruise missile-equipped platforms.

Strike

To examine the strike capability required in the shaping layer first, an important factor for the deterrent value of the Atlantic Bastion (or in determining the resource that the RFN would commit to countering it) is NATO’s capability for maritime strike. How much Allied maritime strike capacity will be held on platforms within the Norwegian Sea, or able to be surged into it? The UK cannot unilaterally generate the scale of threat on which figures such as Admiral Yevmenov speculate, but it can contribute to the Alliance’s ability to present a large threat in several ways. For example, in the short to medium term, the number of MK 41 VLS carriers across the fleet may be increased, and this may have implications for the design of the Royal Navy’s Multi-Role Strike Ship. This could then provide justification for the emplacement of the MK 41 VLS on the Type 31 frigate. While the Type 31 is not particularly resilient considering its limited air defences, it could, as a carrier for tomahawk within larger groupings, both add to total strike capacity and free up platforms such as the Astute class from the Tomahawk Land Attack Missile launching role. In effect, the Type 31 could be envisioned as a proto-arsenal ship in a high intensity conflict with limited self-defence, but with a launch capacity to free up more valuable assets for roles other than strike.

Additionally, if platforms comparable to the US Large Unmanned Surface Vessel (LUSV) were produced, these could host cruise missile systems. The Dutch uncrewed/minimally crewed systems, which are based off commercial vessel hulls, include containerised missile systems. These are used for an air defence role currently, but a similar (probably larger) vessel could plausibly carry a tomahawk system where concentration of strike is deemed critical.

The drive for greater strike capability within the Bastion has implications for the Royal Navy’s plans for a high–low mix carrier air wing, which includes one-way effectors that can be fired from the carrier’s deck. If delivered, these aircraft carriers and their support vessels could provide a forcing function, compelling the Russians to concentrate a (still limited) number of SSNs against them. NATO would then accordingly array ASW assets and potentially include uncrewed systems. Some Russian officers notably anticipate that a NATO uncrewed underwater vehicle (UUV) development will be employed for the protection of high value assets against a Russian submarine threat. In a sense, this is not unlike the Cold War, where aircraft carriers were to be deployed in shallow waters and fjords, compelling SSNs targeting them to transit through prepared minefields.

To the extent that one-way munitions can increase the reach of a carrier’s strike capability, they arguably increase the threat to Russia and therefore increase the value of that capability. This may, in turn, heighten Russia’s desire to prioritise its effort against the carrier. Where NATO ASW resources are stretched, this may allow for an option to concentrate the more active ASW effort in defence of the carriers, in lieu of a more resource-heavy, wider area defence. This option becomes more viable if NATO underwater ISR could saturate the wider geographical areas of the Bastion.

In the longer term, the suggested emphasis on strike has potential implications for the design of SSN-AUKUS. In the context of Russian concerns, the absolute must-have for a future UK SSN is VLS capability, which is currently held solely on the US’s Virginia class. Arguably, a larger SSN-AUKUS (similar to an Ohio SSGN) optimised for VLS size may prove a greater deterrent within the Russian calculus, even if it comes at the cost of the versatility of a smaller hunter-killer SSN (similar to the Virginia class).

Uncrewed ASW

Turning to the second component of the three-layered system, the need for depth and the ability to track Russian SSGNs, both in the near-seas zone and – should Russia choose to surge – beyond it, will be a factor in the success of the Bastion concept. This is fundamentally a question of managing resource scarcity, particularly in a context where the Russians are attempting to dislocate Allied platforms. There is a body of literature that suggests that the employment of large numbers of more expendable uncrewed assets, such as UUVs and medium-sized USVs, may be a viable means of trailing SSNs, allowing Allied SSNs, frigates and maritime patrol aircraft to be freed from the task of trailing adversary submarines.

In the authors’ view, this suggestion is valuable, but shows its limitations when SSNs are surged through the GIUK gap in peacetime. The employment of uncrewed systems against a Russian surge is likely to be constrained by several factors. Most important among these is the trade-off between size (and thus cost) and characteristics such as speed, seaworthiness and the capability to carry (and power) active sensor systems. Most UUVs have a considerable speed disadvantage over targets such as SSNs due to their battery-powered propulsion; they are often designed for endurance rather than speed. Even larger UUVs, such as the extra-large UUV (XLUUV) Orca class, only reach approximately 8 knots. While small, cheap USVs are employed both in commercial roles and in tasks such as mine countermeasures, factors such as endurance operability in high-sea states and payload make ASW in the north a very different task. For example, the Reach Remote 1 USV used in the commercial sector can operate at sea states of 4–5 and has roughly 700 kw of generated power (in addition to battery storage). Similarly, the USV 90 has 12 hours of endurance. Such capabilities can be useful in several roles, including some within the Atlantic Bastion, but they would be of limited value if a target must be tracked over a long distance in tandem with crewed frigates.

Some USVs are being designed to achieve higher speeds, with the US Sea Hunter experimental USV currently capable of reaching 27 knots. However, the power demands of an additional payload (for example, an active sonar) would probably result in a significant reduction in speed. Larger platforms capable of both endurance and of operating an active sonar can be developed, such as the US Navy’s LUSV, which is capable of generating 2,300 kw (which is sufficient for active sonar), and can reach speeds of up to 27 knots. However, the first US LUSV is likely to cost $497 million, which is only marginally less than the Japanese Mogami-class frigate. Admittedly, unit costs for “first in class” considerably exceed subsequent vessels. However, the gulf in cost between several LUSVs and a theatre ASW platform, such as the US Navy’s TAGOS (priced at $434 million), is likely to be marginal, considering that multiple LUSV-type craft would be needed to perform the function of a ship like the T-AGOS. The advantages of deploying uncrewed solutions for active tracking and pursuit therefore do not lie simply in cost.

Smaller, cheaper surface vessels are likely to be more limited in their capability, but could have specific utility within the Bastion depending on how they are integrated and how their endurance is managed, and assuming that they are sufficiently robust to operate in challenging sea states. However, they would probably be unsuitable for broader Atlantic tracking. European navies believe that smaller USVs can be made to operate in up to sea state 5, which would probably put them “out of limits” for significant periods in the High North. Motherships, modelled on the Multi-Role Ocean Surveillance Ship (MROSS) (with RFA PROTEUS as their prototype), could help mitigate these challenges if they are able to recover USVs in high sea states, and potentially provide other operational support. However, unless equipped with active defences, or protected by other assets, such platforms would be at significant risk at the outbreak of conflict, particularly from the submarines they would be attempting to track or detect.

Uncrewed systems used in support of longer-range tracking against a Russian surge may offer other efficiencies, particularly with respect to crewing and persistence, but most probably at costs comparable to crewed assets in this role. This is likely to have significant ramifications for how the Type 92 uncrewed ASW sloop is designed, with a key implication being that scalability and persistence, rather than cost alone, should determine the characteristics of the vessel. Efficiencies could be sought in areas such as platform commonality with the Type 91 missile barge, since a larger design could serve as the basis for both. In effect, the guiding principle for uncrewed systems should be scalability, which is related to – but not the same as – cost. Useful platforms may be large and come with a high cost (comparatively speaking), but can still be more scalable due to the simplicity of manufacture (compared to ultra-quiet guided missile frigates (FFGs)) and crew requirements.

An effort to generate low-cost solutions risks repeating the errors of US Admiral Zumwalt’s high-low mix fleet design, which characterised US planning in the 1970s. In that instance, the effort to drive down the cost of several capabilities, such as the hydrofoil vessel and sea control ship, meant that they were eventually deemed unfit for their tasks, which, in turn, drove large unplanned cost growth. For example, the early-model sea control ships were too slow to keep up with Soviet submarines and too small to maintain persistent tracking by air. The concept was valid, and many of the basic ideas underpinning the sea control ship characterised the use of landing helicopter assault ships as helicopter platforms and “Harrier carriers”. However, the assumption that this would result in a very low-cost capability led to under-resourcing. Similarly, the problem with the low-cost FFG was not conception, but rather an effort to minimise cost through a hydrofoil design. Scalability and low cost are not the same consideration, and a high–low fleet mix can generate less complex (and thus more scalable) capability, just not a very low-cost one. Recognition of this balance should drive naval planning.

However, larger uncrewed systems, although not expendable, can complement frigates. The requirement to track SSNs in the Norwegian Sea, within the Atlantic Bastion, will probably incentivise the use of an active rather than a passive regime. The great average depth of the Norwegian Sea offers advantages with respect to sound transmission in lower frequencies, and the seasonal thermocline of the Norwegian Sea incentivises the employment of variable-depth sonar. While a number of Allied navies field frigates equipped with low-frequency active sonar, questions remain over both platform availability and the risk that Allied vessels take in actively emitting against Russian SSNs. Russian SSNs notably outrange NATO assets by a considerable margin in many instances: the Futlyar torpedo, for example, has twice the range of the MK 54 and the Stingray. Uncrewed platforms acting as emitters and sensors could better exploit the opportunities provided by the hydrodynamics of the Norwegian Sea. The uncrewed systems envisioned as part of the Atlantic Bastion construct could therefore contribute to sea control, but could also could support frigates as they trail contacts into the Atlantic. Moreover, as illustrated by the case of Atrina, it is important to demonstrate to Russian SSGNs that they are being tracked without placing key platforms at risk. Uncrewed assets can use their own active sonar in a (comparatively) less risky way, and thus alert Russian SSGNs to their predicament without placing FFGs at risk. The ability to contribute to tracking through and beyond the Norwegian Sea, and to operate an active sonar, would probably drive platform choices in the direction of larger, costlier uncrewed assets than are sometimes envisioned.

Cheap Networked Systems

This report has so far differed from other research, which suggests that cheaper uncrewed systems can take on a range of roles currently played by crewed ones, including trailing. However, there is an area where a larger number of cheaper networked systems can have greater utility, namely in the first, detection layer, and in contesting the boundary between the Russian near- and far-seas zones (which roughly corresponds to the north of the Atlantic Bastion). This is likely to be an area of concentration for the Class One platforms (SSNs and larger combatants) to which Russia allocates ASuW functions. This category is also likely to include platforms such as the Oscar-class SSGN. Considering the number of missiles that the Russians calculate having to use for ASuW, losing even a limited number of Class One platforms can be highly disruptive to overall planning. The Russians estimate that up to 80 cruise missiles would be needed to penetrate the screen of a NATO formation such as a carrier strike group. For reference, the modernised component of the Russian Backfire force (composed of roughly 30 bombers) can theoretically carry 90 KH-22 cruise missiles in aggregate, although the requirement for speed and range would restrict them to carrying fewer in practice. The retention and modernisation of submarines such as the Oscar II therefore remain important for ASuW, because of the aggregate missile-carrying capacity of these platforms (the Oscar II can notably carry 72 P-800 Oniks anti-ship cruise missiles). The retention of vessels such as the Admiral Nakhimov, and efforts to integrate the 3M22 Zircon on the Gorshkov-class frigate, may also be understood in the context of contesting the far-seas zone. Russia must maximise the VLS capacity at its disposal. If it faces a credible risk of losing a significant portion of the platforms that it holds back for ASuW warfare early in a conflict, it will have less capacity available to surge into the Atlantic.

The primary challenge associated with tracking a submarine such as the Oscar class is not necessarily its quietness. Both its two-shaft propulsion system and its twin reactor make the Oscar a considerably easier target to track than either the Akula or the Yasen, considering the additional sources of broadband and narrowband noise. However, at the northwestern edge of the nearseas zone is the Barents Sea polar front, where the warm water of the North Atlantic meets the waters of the Arctic, forming a polar front through which sound propagation is highly limited. This combination of factors creates tracking challenges for NATO, even against less capable platforms. From the portion of this front that extends south of Svalbard into the Norwegian Sea, the Oscar class can pose a threat to high-value targets, such as aircraft carriers or surface vessels equipped with cruise missiles, while limiting the impact of its own noisiness. Although constrained by limited air- and space-based ISR, and by the range of its antiship cruise missile (the P800 Oniks), the Oscar class would nonetheless pose a credible threat to NATO surface vessels out to 400 km from the polar front. That would amount to a total distance of roughly 1,500 km from Russian shores – well into the farseas zone. In addition, this area falls within the Russian air A2/AD envelope, where air force interceptors such as the MIG-31BM equipped with the R-77 would pose a credible risk to maritime patrol aircrafts supporting the NATO ASW campaign. This would mitigate for Russia, but not eliminate, the vulnerability of both noisier SSGNs and larger surface platforms. An effective employment of the Oscar class by Russia, if uncountered, could essentially achieve sea denial out to 1,500 km. If NATO operated from beyond this distance, it would significantly constrain the effectiveness of its tomahawk-carrying platforms: while the maximum range of the Tomahawk Land Attack Missile exceeds 1,500 km, a missile’s room for manoeuvre is likely to be constrained past this point.

The challenge of containing vessels in the polar front would be exacerbated in the build-up to a conflict by a probable targeting of NATO’s IUSS. Soviet targeting of the Sound Surveillance System during the Cold War, and more recent attacks on cables near Lofoten, point to this as a probable course of action. It therefore cannot be presumed that the IUSS will provide cueing against a vessel transiting from the Barents to the Norwegian Sea.

A combination of the complex acoustic environment, and the fact that Russia is likely to mine approaches to this area relatively early in a conflict, could partially (but not entirely) offset the advantages in quietness and sensor capability that Allied SSNs enjoy over both older SSNs and diesel electric submarines, which Russia might employ in defensive roles. The sophisticated conformal array sonar on submarines such as the Virginia class would provide relative advantages to NATO, irrespective of the environment, over submarines such as the Sierra and Akula (which use older cylindrical array sonar). However, a significant mutual risk remains in the complex waters of the Barents Sea, as illustrated by the example of a 1993 collision between a Sierra class and a Los Angeles-class submarine, which had failed to detect one another.

Equally, if the polar front were not viewed as providing cover for noisier Russian SSGNs, this would affect operational choices, including the way in which quieter SSGNs would be allocated. An early goal for NATO should therefore be the provision of persistent undersea ISR, initially in a comparatively limited part of the Barents Sea polar front. Although not necessarily suitable for tracking targets over long distances, sensors on underwater gliders and smaller UUVs can serve a number of roles, including cataloguing the salinity and temperature gradients within the polar front, receiving active sonar returns further forward (with fewer transmission losses), and providing persistent passive detection. One of the significant issues with some of these systems is the transmission and collation of data gathered, as much of the information is not received in real time due to underwater communication constraints. Additionally, variable-depth sensors such as Towed Reelable Active Passive Sonar could be employed on relatively low-cost platform USVs to saturate likely launch areas (accepting that some systems will be lost in high sea states). Naturally, these emerging technologies would be expected to be used in combination with other more traditional equipment, such as sonobuoys, where appropriate. Using and combining a variety of systems is not without complexities, including around underwater communications, identifying optimal pathways for data transfer, and having high rates of data processing and collation. The ability to move data will probably depend on whether it is possible to move data quickly to the surface, or process it “at the edge” to allow smaller volumes of data to be moved. However, it should be noted that the greater the amount of processing at the edge, the less latency is required. For example, US DIFAR sonobuoys (which perform some on-board processing) can communicate via high-frequency radio.

Notably, it is not just in the Polar area where the networking of remote sensor systems will have utility, as is evidenced by the push to develop Atlantic Net (as a first stage of the Atlantic Bastion). As part of project Cabot, the aim is to deploy these systems in the GIUK. Most naval strategists expect that there will be iterative improvements on multiple strands of Allied effort in sensors and uncrewed systems, where it will be key to ensure constant compatibility and integration. Most notably, permanent and semi-permanent systems could be established by NATO within exclusive economic zones and areas where it has peacetime sea control. These will assist with many of its data and communication challenges. Assuming that relatively cheap sensors would be distributed in a crisis leading to a conflict, the platforms used to distribute them need not themselves be highly survivable, as – much like Russian SSNs – they would operate with relative impunity in this period. Consequently, auxiliary or converted vessels such as the MROSS, which might have limited survivability in a conflict, could be viable platforms for laying sensors in a crisis. Several Russian documents appear to anticipate the movement of uncrewed systems and motherships into the theatre as being an indicator of the buildup to a conflict. As this movement is a visible process, it can serve as a means of both signalling conflict and preparing for it. More easily observable motherships based on civilian designs, which are overtly preparing defences for conflict, may therefore serve a deterrent role in addition to generating cost savings. Ideally, much of this coverage can eventually be scaled to the Norwegian Sea as a whole.

Comprehensive subsea sensing coverage and domain awareness are already practised by some nations within territorial waters and clearly defined points of interest. This is illustrated by China having invested in protecting key parts of the South China Sea, such as Hainan island (where China’s SSBNs are based), using a network of sensors. These include underwater gliders, USVs and “integrated floating ocean platforms”, which are larger stationary platforms carrying multiple sensors. These sensors were emplaced initially by commercial (but stateowned) actors such as the China Electronics Technology Group Corporation in support of maritime domain awareness, with the objective that the PLA will eventually be able to benefit from them.

Mine Warfare

A key capability that is currently underexplored by NATO, but particularly by the UK, is the potential for using protective and defensive minefields in peacetime. In the authors’ opinion, this is a key capability that should form part of the Atlantic Bastion design, as many capabilities (such as UUVs) can be relatively easily weaponised. The threat to both surface and subsurface Russian Class One assets will affect the confidence with which they can be used to deny NATO freedom of action in Russia’s near seas zone and coastal defence zone. British, or at least NATO, capability for offensive mining – particularly if undertaken remotely and in areas of little or no expected civilian traffic – is a wartime measure that might significantly affect Russian deterrence calculus. NATO’s defensive deterrent posture can be bolstered by mining, mobile mines and mines that can be laid (but not necessarily armed) from out of area. Naturally, there are key legal implications, particularly in the case of minelaying during peacetime (even if the mines are not armed, but primed for remote arming). Even where mines are not legally prohibited, the provocative and potentially escalatory nature of such activity must be taken into account. Mining could be seen as giving a green light to similar or more aggressive reciprocal activity by the adversary.

Uncrewed systems such as XLUUVs can act as minelaying platforms in peacetime, by placing influence ground mines. Autonomous means of laying the Mark 60 CAPTOR (the US deepwater “torpedo”-type mine) could presumably also be developed. The CAPTOR can be air dropped, but others, such as the US Quickstrike Extended Range, can be dropped at a range of up to 40 nautical miles and from high altitude. This minimises the risk to minelaying aircraft, while also signalling to the adversary that minelaying is taking or has taken place. Smart naval mines can benefit from other underwater ISR feeds, paired with remote sensors for targeting data collection and transmission, to adjust minefields dynamically based on real-time conditions. A crucial deterrent force multiplier for the UK would be to ensure that the Atlantic Bastion is capable of being integrated with the minelaying systems and practices of other NATO nations, even where the UK continues to reject development of a minelaying capability. Having a clearly articulated mine usage intent and capability would serve to deter Russia by protecting home seas from sabotage or intensified hybrid activity, and by projecting sea denial into hostile waters in case of conflict.

It must be noted that Russian mine-hunting capability currently appears to be spearheaded by the Project 12700 Alexadrit-class vessel. Russia’s adherence to a hull-based system will arguably reduce its clearance capability in contested environments; being able to operate in such high risk areas with reduced risk to life, is one the key benefits of some of the autonomous systems being developed by NATO. The natural corollary to this is ensuring that any similar mining intent on the part of an aggressor (Russia) can be frustrated by the Atlantic Bastion. NATO and Royal Navy mine-hunting and mine-disposal capability should be a key consideration in the design of the Bastion. Ensuring that NATO mine-hunting capability – especially its autonomous and remote systems – can benefit from persistent undersea ISR would be key to time-sensitive clearance efforts, should the Russians achieve clandestine and/or remote minelaying within the Bastion areas either prior to or during conflict. Effective ISR data could help in identifying minelaying activity and focusing subsequent hunting efforts.

Last, the employment of UUVs as a type of loitering munition is also theoretically viable, as the major difference between a sophisticated torpedo such as the MK 48 and a hypothetical UUV used in the same role is their method of propulsion, rather than their sensors or processing. This is particularly useful against platforms such as the Kirov. While these platforms are unlikely to be survivable in the long term, salvo combat models suggest that vessels with the size and air-defence capacity of the Kirov can absorb a disproportionate number of air-launched munitions, thereby impacting wider planning.

Situational Awareness

One of the fundamental aims of the Atlantic Bastion is about situation awareness; to be able to detect Russian submarine movement and to demonstrate NATO’s ability to this to the RFN. However, the final observation that the authors make is that situational awareness ought to be understood in relative rather than absolute terms. Situational awareness is not just about understanding an opponent’s location but also disrupting the opponent’s understanding. This has historically been a feature of ASW. During the Cold War, for example, Julie Jezebel sonobuoys simulated the acoustic profile of a depth charge and were used by the US Navy to disrupt the activity of Soviet submarines. In the context of surface warfare, the use of decoy vessels to spoof electronic intelligence was an important feature of both Cold War exercises, such as exercise Haystack, and carrier deployments. Many uncrewed capabilities that may not necessarily have sufficient seaworthiness or payload capacity to carry high-powered sensors can still act as acoustic decoys, emitting sounds that emulate the profile of a more valuable target.

This capability extends beyond acoustics. Both within the near-seas zone and immediately beyond it, the employment of standoff capabilities has become an integral part of Russian planning for submarines. While these aspects are well understood, some of the implications for both planning and non-acoustic methods of detection deserve further discussion. According to Russian military journals, the primary existing mechanisms for communication with submarines are satellite communication downlinks, and bouncing high-frequency radio waves off the ionosphere. Some Russian authors have noted the poor latency associated with high-frequency communication, which they estimate to be around 1.2 kb/s. For reference, the mission file on a land-attack cruise missile is around 10 MB in size. This would suggest relatively long transmission times and lead to kill chains being fragile to disruption in the electromagnetic spectrum. In the same way that UAVs have become a relatively expendable means of both intercepting and spoofing electronic emissions in land warfare, they could play a similar role in the maritime domain in areas where crewed electronic-warfare aircraft cannot be risked.

Conclusion and Recommendations

This paper has made recommendations for how the deterrent value of the Atlantic Bastion can be further enhanced, and for how its general utility can be improved beyond that of a defensive buffer. These recommendations are founded on an understanding of Russian deterrent risk calculus; the Russian General Staff’s modest strategic expectations for the RFN in the maritime domain (beyond the delivery of their nuclear deterrent); and the risk that the Atlantic Bastion could be bypassed by Russia as it currently stands, especially in peacetime.

This paper’s proposals represent a refinement of the concept rather than a critique as such. If what emerges from the Atlantic Bastion concept is a barrier capability based around low-cost sensors that are primarily deployable in the Norwegian Sea, this will represent a maritime Maginot Line, which the RFN will probably circumvent. To blunt a surge, at least some of the platforms in the Bastion must be able to augment NATO’s crewed FFGs in tracking SSNs beyond it. The ability to track SSNs over long distances with active sonar would make it much harder for Russian planners to assume that they can lose their pursuers in the Sargasso Sea. Uncrewed systems, which can use active sonar with less risk than crewed ones, can play a valuable role here. However, this requirement will drive up the cost and complexity of USVs.

There is a role for cheaper, more static sensors and mines. However, this role is just beyond the current confines of the Bastion in the western Barents Sea. Sensors here can cue larger platforms, which must continue trailing SSGNs in the Norwegian Sea and beyond. If weaponised, these sensors would act as a mine threat to SSGNs such as the Oscar class, which represent the primary ASuW threat to Allied carriers.

In effect, then, the vision of the Atlantic Bastion that the authors present is one that dilates both east and west. The best use of static sensors is under the polar front to the east, while those USVs used in the Norwegian Sea must be large enough to support tracking to the west.

Finally, to the extent that the Bastion is tied to an increase in Allied long-range strike capacity, it will be harder for Russia to ignore or circumvent.

Key Findings and Recommendations

• The most likely RFN response to the Atlantic Bastion is to surge nuclear-armed submarines into the Atlantic. This surge will either bypass the Bastion or move through it under peacetime (pre-conflict) rule.

• This makes depth – the ability to track contacts beyond the Bastion – critical, considering that the Russians will seek to transit pre-conflict and lose trackers in the Sargasso Sea. Freeing up crewed assets for this role can be one function of the Bastion, but larger uncrewed systems can also play an important role in providing depth.

• To enhance its deterrent effect, the Atlantic Bastion should include or be able to host a significant quantity of maritime strike capacity, most realistically in the form of missiles carried in VLS (such as Tomahawk cruise missiles).

• The UK and European NATO allies will need to provide a significant proportion of the maritime strike capacity within the Bastion to mitigate potential US re-tasking to the wider Atlantic or Pacific.

• The Atlantic Bastion will not obviate the requirement for exquisite, crewed antisubmarine platforms, but will improve their effectiveness and efficiency.

• USVs required to support active anti-submarine tracking will need to be of a significant size due to power, endurance and seakeeping requirements. Although cheaper than crewed systems, they will, in many cases, not constitute “cheap mass”. However, this is not uniformly the case, and there is a specific important use case for cheaper uncrewed systems in the Barents Sea polar front.

• NATO should consider enhancing its sea-mining capability.

• The UK Royal Navy Submarine Service should regain its under-ice capability as soon as practicable.

Sidharth Kaushal is a Senior Research Fellow in Seapower at RUSI. His research at RUSI covers the impact of technology on maritime doctrine in the 21st century and the role of seapower in a state’s grand strategy.

Edward Black is the First Sea Lord’s Visiting Fellow at RUSI. His research interests include maritime power and defence engagement. As a mine clearance diving officer, in addition to his time at sea, he has served extensively abroad including operational tours in Afghanistan and Bahrain; loan service with the Royal Navy of Oman; and as defence attaché in Mali and Deputy Defence Advisor in Kenya.