British Grand Strategy and Hedging in Europe: The Case for Nuclear Arming

Introduction

Britain faces the most turbulent geopolitical landscape since the early Cold War. An emboldened Russia is adapting to drone-based warfare in Ukraine, mounting covert operations across North Atlantic Treaty Organization (NATO) territory, and helping Beijing prepare to absorb Taiwan. European militaries, for their part, remain under-equipped and unable to rapidly deploy eastward in force.

At the same time, U.S. foreign policy is in flux. America has been tied to Europe since the early Cold War by intertwined economic, ideological, and strategic imperatives. Compared to its post-World War II predecessors, however, the second Trump administration takes a minimalist view of U.S. interests on the continent, and while outright NATO withdrawal remains unlikely in the immediate future, de facto disengagement is well underway.

In Britain, most commentators favor higher spending on military forces, but how such spending would enhance the country’s security is often left vague or implicit. For grand-strategic analysis, however, explicit means-ends reasoning is crucial. Many explicit arguments suggest allocating scarce resources to conventional forces, especially ground forces. From this perspective, Britain’s nuclear deterrent remains adequate, given its potency and invulnerability, whereas the UK’s inability to sustain a full-scale conventional war against a peer competitor, namely Russia, requires urgent redress.

This essay argues that the standard view misconstrues Britain’s threat environment. While its strategic nuclear deterrent remains largely secure, vulnerabilities exist and may increase, growing in salience as America disengages. At the same time, the strategic deterrent is ill-suited to crises with less-than-existential stakes; short of large-scale attacks on the UK mainland, Russian leaders might well discount British nuclear threats. To minimise its strategic vulnerability, London must operate at least one additional submarine; to support its posture in Europe, a tactical nuclear option should be reacquired. While both measures are commonly portrayed as prohibitively costly, London should prioritise nuclear arming over a broad conventional buildup.

The relevance of grand strategy

“Grand strategy” is discussed much less often in the British than in the American, Russian or Chinese contexts. UK officials have stated publicly that the country either cannot formulate or does not require a grand strategy, in light of the relative tranquility, or later “complexity,” of the post-Cold War environment. 

For many commentators on both left and right, the discussion itself appears naïve or quaint, given the country’s role as a satellite or client of the American empire. “The hidden fist of the US empire,” writes Matt Kennard, “which I’d seen deployed all over the developing world – the massive American military – [is] also occupying Britain” in the form of U.S. air force installations. Neema Parvini similarly dismisses “the fiction that Liz Truss or Boris Johnson... have been leaders of the autonomous Government of the United Kingdom rather than a supine regional vassal state.”

A grand strategy, however, is not the exclusive preserve of great powers or vestige of a simpler era, but rather a state’s theory of security. A client state ventriloquized by another power lacks a grand strategy of its own, of course, but Britain is not a U.S. client. While the global distribution of military power remains unipolar, the current international system—including the institutionally integrated “liberal international order” sub-system—is a balance-of-power order composed of domestically ruled nation-states.

U.S. power preponderance naturally provides Washington with extensive leverage, yet that leverage is bounded, for two main reasons. First, although a larger power advantage makes a given threat more credible, potential targets will also be less inclined to consider the threat in isolation and more likely to anticipate expansive future demands; compliance becomes unappealing when the resulting reprieve is seen as temporary. Second, the balance of power is distinct from the distribution of usable military capabilities. Despite unparalleled power-projection tools, for example, Washington cannot plausibly threaten the territorial integrity of—nor therefore powerfully coerce—sovereign states that possess or could rapidly acquire a robust nuclear capability.

Although the U.S. military retains much of its Cold War-era overseas basing network, including in Britain, a military presence in itself does not constitute indirect rule. Indeed, American strategy in the unipolar era has been less “imperial” than prior to 1989, as Washington has less frequently sought to exert major pressure on allies and host states.

Of course, ostensibly interstate relations can shroud hierarchical relations between regimes. One state might rule another indirectly, elevating like-minded or pliable elites through regime-level security guarantees, conditional aid, or electoral manipulation to produce desired policy outcomes. During the early Cold War, Washington molded West European politics by employing these and other methods to bolster anti-Soviet and pro-American domestic factions. 

In Britain, however, the postwar Labour Party’s anti-Soviet posture gave the U.S. neither a strong incentive nor a viable means to exert influence. “The United States did not attempt to manipulate Britain’s internal politics and allowed autonomous political processes to unfold,” notes David Lake, “for two critical reasons. First, United States and British policy preferences were more closely aligned than elsewhere... Second, the similarity in the foreign policy preferences of the two major political parties in Britain—Labour and Conservative—limited the ability of the United States to impose indirect rule,” since “[t]ipping the balance of political power in one direction or the other would have produced little difference in Britain’s foreign policy.” 

It is thus unsurprising that British officials have often either resisted American demands, as in the case of Margaret Thatcher’s refusal to back Ronald Reagan’s nuclear disarmament initiative, or actively advanced them for their own reasons, as in Britain’s involvement in the invasion of Iraq. Overall, as William James concludes in a recent study, “American influence over British grand strategy has been greatly exaggerated.” 

A second objection to talk of “British grand strategy” emphasises the long-term decline in the UK’s relative power, its anemic productivity growth following the 2008 financial crisis and the chastening stability operations in Afghanistan and Iraq. Grand-strategic debates, in this view, are a distraction from the more piecemeal approach befitting a formerly great power.

Britain’s military potential is indeed limited. While power cannot be measured precisely, a coherent definition should account for variation in states’ welfare and security costs, as well as their efficiency at converting resources into military capabilities. Michael Beckley’s rough proxy for relative net resources, which compares the products of states’ total GDP and GDP per capita, is a useful first-pass, and according to this measure, Russia’s power advantage over Britain was around 5:4 in 2024, China held a nearly 4:1 advantage, and America’s stood at more than 9:1.

Declining power does not lessen the need to carefully formulate grand strategy, however. On the contrary, a less capable state operates in a more dangerous environment, leaving its security more rather than less sensitive to suboptimal military policies. 

More fundamentally, the level of security a state derives from its relative power in a specific context is mediated by the offence-defence balance, or the relative cost of the forces required to overcome a given defending force. When a state is surrounded by water, for example, or acquires nuclear weapons, even far more powerful rivals may be unable to translate their advantage in military assets into operational success or coercive leverage. Accordingly, modern realist theories of international relations focus on military capabilities rather than relative power.

U.S. Withdrawal from NATO is Plausible

Beyond power and offence-defence variables, a coherent grand strategy must make judgements about a state’s potential allies. In any serious military contingency since the Second World War, the UK would almost certainly have acted alongside the U.S., insulating Britain’s security from changes in its sovereign military capabilities.

Today, however, the British government should plan as though Europe’s post-World War II security arrangements are no longer in place. While predicting even near-term U.S. strategy is now far from straightforward, when uncertainty is high decision-makers should rationally focus on the plausible worst-case, and de facto American withdrawal from NATO should be viewed as eminently plausible, for several reasons.

Most obviously, Trump’s longstanding worldview sits uneasily beside the NATO commitment. Unlike in his first term, however, senior officials in his administration are also deeply skeptical of its overall benefits. As a useful simplification, we can divide officials into four factions.

First, an Atlanticist old guard (“neocons” in common parlance), composed of Republican elder statesmen, assorted hawks and liberal interventionists, favors deep and open-ended military engagement in Europe. In their view, U.S. primacy is necessary for suppressing regional security dilemmas, deterring potential revisionists, preserving liberal-democratic governance, and sustaining open trade relations. The Atlanticists narrowly averted fundamental revisions in U.S. grand strategy during Trump’s first term, but are now largely absent from senior policy roles.

The second, comprised of conservative nationalists, paleoconservatives, and libertarian anti-interventionists, advances a minimalist conception of America’s overseas security interests and a highly skeptical view of aid to Ukraine. Though ideologically diverse, this faction cleanly rejects the premises of U.S. international primacy. Its most influential voice inside the White House is Vice President JD Vance, whose stated indifference to the outcome in Ukraine and contempt for Europe’s dependence on U.S. power projection have visibly unnerved the continent’s elites. 

A third grouping is a cohort of self-described realists—a moniker that, in a military policy context, commonly signifies “restraint,” i.e. a preference for “offshore balancing” over the forward deployment of combat forces and a relative uninterest in non-security goals, often coupled with a presumption that other major powers’ aggressive behaviours are motivated by insecurity. That presumption, which Trump sometimes seems to share, would give officials little reason to expect large-scale Russian aggression in Europe beyond Ukraine, while offshore balancing and a security-only focus provide no immediate reason to intervene.

Lastly, more hawkish policy realists within the administration also deemphasise non-security goals, but interpret Moscow and Beijing’s aims as less defensive, and therefore less responsive to reassurance about U.S. intentions, than do their restrainer counterparts. Still, given China’s much greater economic and military power, these officials prioritise enhancing American warfighting capability in East Asia at the expense of competing with Russia in Europe. As the Pentagon’s lead policy official Elbridge Colby has written, “the US interest in Europe must be shaped by the requirements for ensuring that China does not establish predominance in Asia.”

The extent of these four factions’ individual or collective influence, in the face of organizational inertia and Trump’s mercurial temperament, is debatable. But Europe’s policymakers should note that most GOP voters now have an “unfavorable” view of NATO, many influential American commentators endorse U.S. withdrawal, and factions even less committed to European security may well dominate the 2028 Republican primary. Needless to say, U.S. allies would be unwise to base their national security on the Democratic Party’s electoral success.

Beyond the Trump administration’s ideological composition, Europeans should also keep in mind the looseness of the security guarantee embedded in the North Atlantic Treaty. “Guarantee” is of course a misnomer; states will take costly and risky steps, such as military interventions, only insofar as such steps serve their current interests. But Article 5 of the Treaty does not even notionally commit the U.S. to defend a co-signatory. Instead, parties merely “agree that, if such an armed attack occurs, each of them... will assist the Party or Parties so attacked by taking forthwith… such action as it deems necessary [emphasis added], including the use of armed force, to restore and maintain the security of the North Atlantic area.”

The Truman administration kept the Treaty’s original language vague partly to mollify congressional and popular aversion to foreign entanglements, selling Article 5 to Congress by emphasizing its noncommittal letter over its eventual spirit. A large share of the American public knew the Treaty contained no ironclad pledge to go to war and conditioned their support on its absence.

But there was also no consensus, even among top administration officials, on why the U.S. should intervene in a European conflict. Traditional accounts of the American commitment stress the perceived need to prevent a single power from occupying the industrial centers of Eurasia, as their vast combined resources would allow it to ultimately conquer North America. But that fear rested on the premise, which not all officials seem to have accepted, that large invasion forces could still be moved across wide, contested oceans in a world of mass air power and nuclear weapons. In fact, many on both sides of the initial American debate over NATO agreed that a Soviet takeover of Europe may not deal a fatal blow to U.S. security.

Nonetheless, the survival of non-communist Europe was seen as a near-vital interest for various reasons, not all of them material. “With a totalitarian Europe which would have no regard for individual freedom,” noted one government committee, “our spiritual loss would be incalculable.” By the early 1960s, a de facto security commitment had emerged, underwritten by the forward deployment of large U.S. conventional and tactical nuclear forces. 

Many American officials, to be sure, would have strongly preferred European states to address the Soviet threat themselves. They were deeply divided, however, over the so-called “German question.” The heart of the issue was that for noncommunist Europe to balance Soviet military power, West Germany’s latent capabilities would have to be leveraged, but for Bonn, meeting the Soviet threat inevitably meant acquiring formidable nuclear forces. The West Germans, for their part, were eager to acquire nuclear weapons. Yet the Soviets were fiercely opposed, initiating major crises around Berlin in the late 1950s and early 1960s in their effort to compel Washington to withhold nuclear weapons from the Germans. 

Eisenhower and Kennedy took different tacks. The Eisenhower administration saw West German proliferation as a way to reduce the fiscal burden of superpower competition. Under his direction, Bundeswehr units were given de facto control over some forward-based American nuclear systems. The Kennedy administration, by contrast, was prepared to reduce tensions with Moscow by blocking Bonn’s nuclear ambitions, and aimed to preserve U.S. preeminence within the collective West. To these ends, Washington reasserted sovereign control over all forward-based nuclear weapons, and to discourage unilateral proliferation, threatened to withdraw U.S. conventional forces from the continent more rapidly than the West Germans would be able to acquire a nuclear arsenal.

In its about-face on the German question, the Kennedy administration succeeded in paving over the most dangerous source of tension in the postwar world. At the same time, the arrangement solidified Europe’s dependence on U.S. military capabilities for the remainder of the Cold War. Such dependence naturally gave Washington a degree of leverage over European affairs; in the decades that followed, the U.S. sought to keep its core allies commercially open, politically liberal, and geopolitically subordinate. Not coincidentally, this arrangement helped ensure that any future collapse of Soviet power would give rise to an era of U.S. unipolarity.

In the present unipolar order, Moscow cannot plausibly aspire to dominate Europe, much less Eurasia, so the region plays a proportionally lesser role in overall U.S. strategy. Yet the German question still looms. “The heart of the problem” for America and Europe today, writes Marc Trachtenberg, “concerns not Ukraine but Germany, especially the question of whether that country should possess nuclear forces… Few people, either in Germany or the other Western countries, are comfortable dealing with that issue openly.” In Washington, concerns about the ripple effects of disengaging from Europe may continue to outweigh the strategic, and more importantly domestic, pressures to retrench. After all, unease about the prospect of German proliferation is the fundamental reason why the NATO system endured after 1991.

That unease has never been based on a purely structural analysis of European geopolitics, however. Although reasonable analyses could come to different conclusions, it is difficult to characterize the British and French nuclear forces as fixtures of European stability while regarding a hypothetical German force as a severe threat. Rather, concerns over German proliferation stem largely from a particular suspicion about the country’s belligerent disposition. “[O]ne has the sense that most non-Germans oppose the idea of a nuclearized Germany” Trachtenberg notes, “because they still deeply distrust the Germans on a visceral level; German behavior during the Nazi period was so horrifying that even the other Western countries cannot quite bring themselves to trust the Germans the same way they trust each other.”

And yet, as U.S. policy in the Cold War shows, statesmen can and do approach the issue differently. In the end, Europeans would be reckless to assume future U.S. administrations will answer the German question the same way Kennedy did, especially without a rival great power all but forcing their hand.

Grand-strategic independence

As the U.S. commitment has frayed, recent British governments have set increasingly ambitious targets for defence spending. Yet, when untethered to specific scenarios, military spending can be only loosely correlated with capability.

To hedge against American disengagement, Britain would need to adopt a much more independent grand strategy in Europe. Grand-strategic independence does not necessarily imply relinquishing commitments or abandoning non-security goals; the security value of maintaining NATO states’ territorial integrity or Ukraine’s survival would be a matter of debate, and London could continue to pursue broad aims. 

But a more independent grand strategy will require sovereign military forces capable of deterring or defeating large-scale threats to the homeland and resisting coercion by hostile powers. For Britain, of course, military self-sufficiency would be a departure from post-World War II grand strategy. Historically, however, capable states have often been reluctant to rely on allied support.

Military policy implications of U.S. disengagement

There is already a consensus on the need for large increases in military spending, primarily on conventional forces, as a hedge against U.S. disengagement. On the nuclear side, meanwhile, many also contend that Britain’s forces remain adequate, given their capacity to inflict unacceptable damage on the country’s main state adversary, Russia.

But this view misconstrues the UK’s military weaknesses. Currently, Britain can reliably deter existential threats with its secure second-strike capability. However, this “minimal” deterrent, as strategy documents refer to it, could become increasingly vulnerable to attack, or at least perceived as such. At the same time, Britain’s ability to bargain over important but less-than-vital interests is curtailed by a lack of limited nuclear options. The result is that, in an intense crisis, Britain would struggle to credibly threaten nuclear use, either initially or in response to limited Russian use.

The following analysis does not try to predict the overall outcome of U.S. disengagement, or the probable impact on Britain’s existing priorities, nor does it evaluate those priorities. We instead take London’s basic strategic aims as given in order to focus on the narrow military policy implications of U.S. retrenchment in Europe.

Strategic context: The Anglo-Russian security dilemma

To gauge the threat an adversary poses, a state must assess both the military balance and the rival’s aims, in particular whether it harbours non-security or “greedy” aims with respect to the state’s interests.

Discerning a rival’s underlying aims matters because its aims determine how it will react to different policies. At first glance, standard realist theory might seem to prescribe competitive military policies in all cases. States, however, often face a security dilemma, wherein the measures they take to enhance their own security decrease the security of a rival and thus alter its behavior in potentially dangerous ways. The distinction between security and non-security motives is crucial here because policies designed to reassure an ostensibly insecure rival that is in fact driven by a greedy desire for expansion would erode deterrence, whereas treating a genuinely insecure rival as though it were greedy could provoke it into an arms buildup to restore its defences, diplomatic belligerence to signal resolve, and as a last resort, preventive war to neutralize the perceived threat.

While almost all observers view the Russian Federation as Britain’s principal state adversary, President Vladimir Putin’s motives and threat perceptions remain widely debated. Some observers view Russia’s invasion of Ukraine as a last-ditch effort to preserve a wide buffer zone against future Western conventional aggression or the close-in deployment of nuclear forces. Others interpret these stated rationales as pretextual, arguing that the war was motivated by Putin’s ambition to restore Russia’s great-power status or the need to neutralise a simmering threat to his domestic legitimacy.

Fortunately, the wisdom of the policies discussed here is not highly sensitive to assumptions about Russian motives. If Putin’s actions in Ukraine are in fact driven by perceived military vulnerability, Britain’s nuclear security dilemma is not severe since its capabilities fall well short of threatening Russia’s ability to destroy Britain’s cities. Moreover, if Russian authorities were to grow concerned, they would be unlikely to resort to the dangerous policies associated with a severe conventional security dilemma, as those policies would be ineffective. As Brendan Green summarises, in a nuclear world “an insecure adversary cannot affect the military balance by conquering territory, adding strategic depth, or conventionally punishing the adversary army.” Instead, “their only choice is redoubled nuclear competition.”

The prospects for nuclear arms control

Arms control can play an important role in a state’s grand strategy. Britain has never concluded a bilateral nuclear arms limitation agreement, and Anglo-Russian diplomacy remains on ice, yet opportunities might arise. If so, however, London’s approach ought to be guided by a clear view of the purpose of arms control among states with fundamental conflicts of interest.

In most dovish commentary, arms control agreements serve as alternatives to dangerous and futile arms races. Many cite the U.S.-Soviet Strategic Arms Limitation Talks of the early 1970s as a rare instance of high-mindedness overcoming narrow self-interest and, perhaps paradoxically, ultimately serving it.

But when the tension between two states stems from an actual conflict of interest, as opposed to fundamentally unwarranted suspicion, states will tend to compete for military advantage. Arms control can still be feasible and useful, but as an element of the broader competitive process rather than an alternative. By limiting specific weapon systems, arms agreements allow states to place bets on those systems’ future strategic value. When U.S. and Soviet leaders agreed to freeze the ICBM buildup, they locked in Moscow’s quantitative advantage—something its command economy already gave it a good chance of preserving across a drawn-out race—while simultaneously allowing Washington to leverage its technological advantages to enhance its arsenal’s lethality against the Soviets’ numerically superior forces. The upshot for policymakers is that providing incentives for a rival to negotiate an agreement and disincentives for it to subsequently defect means pursuing (and credibly threatening to pursue) policies which threaten the rival’s military position.

Hawkish commentators also tend to wrongly equate arms control with détente. According to many observers, an agreement is only desirable to the extent that it transforms all or many of the adversary’s objectionable behaviors. For example, critics of the 2015 Iran Nuclear Deal frequently argued that Tehran’s support for hostile paramilitary groups made a mockery of the agreement by betraying the regime’s lack of interest in genuine cooperation. In future Anglo-Russian talks, analysts may similarly point to Moscow’s intransigence on Ukraine or covert action in Europe as ruling out any arms control agreement. 

Framing arms control as a competitive interaction, however, makes clear that Russia’s actions in other domains are irrelevant. Instead, arms agreements should be graded narrowly in terms of their impact on UK security. Overall, as long as fundamental conflicts of interest persist, British officials ought to recognise that arms agreements depend on, and serve as a component of, effective military competition.

Entrenching MAD: The case for multiple submarine patrols

Britain’s strategic nuclear posture was formulated, and only remains adequate, under the assumption of close U.S. alignment. The country relies on a fleet of four Vanguard-class nuclear ballistic missile submarines (SSBNs), with one on constant patrol to uphold a continuous-at-sea deterrent (CASD) posture. 

Russia’s nuclear stockpile dwarfs Britain’s arsenal, enabling it to strike the UK mainland with many more warheads than vice versa. Asymmetries in force size only matter, however, inasmuch as they produce a politically salient difference in vulnerability. “Countervalue” capabilities exhibit sharp diminishing returns; when both sides’ major cities can be destroyed at will, as in the Anglo-Russian case, “mutual assured destruction” (MAD) effectively holds, so that even a large imbalance in deliverable warheads will not translate into lopsided leverage. In principle, even a single surviving SSBN—carrying eight Trident II submarine-launched ballistic missiles (SLBMs) each typically armed with five 100-kiloton Holbrook thermonuclear warheads—is probably sufficient to destroy Russia as a functioning political entity.

CASD is also the appropriate posture. Constructing silo fields, as one government report noted, “is entirely impractical in the UK.” The three fields in the U.S. currently hosting America’s Minuteman ICBM force, for comparison, span the equivalent of 43% of Britain’s landmass. The UK would not require as large an arsenal, but fixed ICBMs are increasingly vulnerable. SSBNs, in contrast, remain highly survivable; like their American Ohio-class counterparts, Britain’s SSBNs operate in deep waters far from major shipping lanes, and are quieter than Russian and Chinese submarines. 

Relevant technologies are advancing rapidly. The UK’s reliance on small undersea nuclear forces leaves its security highly sensitive to technological innovation. In Tom Layhe’s words, “the UK is the only nuclear power where developments in the anti-submarine warfare (ASW) domain concern its entire deterrence delivery capability.”

Fortunately, although SSBNs face a growing array of potential threats, for the foreseeable future these threats can be addressed. As in the Cold War, threats to submarines will centre around acoustic detection and tracking at sea, and as before, both passive and active sonars face major obstacles. British and U.S. SSBNs remain extremely quiet, and the inherent trade-off between passive sonar sensitivity and false-alarm rates should prevent SSBN hunters from keeping pace, especially given the rise in ambient noise from commercial shipping. Active sonars, on the other hand, can be highly effective at close range, but emitters reveal their presence to a target much further out than vice versa, allowing SSBNs to evade or to maneuver near friendly naval assets to “delouse” potential trackers.

Other threats to SSBNs also seem limited. The simplest scenario would involve a locatable “tag” being covertly placed on a vessel while in port or attached while en route to its dive site. However, tight security measures inside Faslane as well as thick surrounding air, surface and undersea coverage make successful tagging extremely improbable. More speculatively, innovation in uncrewed underwater vehicles (UUVs) will boost “anti-SSBN” operations, yet there is no obvious way to overcome the cross-cutting challenges of endurance, speed, communication and quieting. At the same time, more advanced UUVs can serve as more effective pro-SSBN decoys and minehunters. Progress in artificial intelligence (AI) is highly uncertain, but at this stage seems unlikely to asymmetrically bolster anti-SSBN forces in the near term. Overall, trends suggest that Russia and China will not be able to jeopardise Britain’s CASD in the foreseeable future.

But there are four important caveats to this optimistic conclusion. First, it describes the likely outcome of optimal or near-optimal policies that enable both sides to operate close to the technological limit. It suggests that British SSBNs can remain survivable, not that they will automatically. Extensive and continuous research, testing and maintenance will be needed to anticipate and address looming ASW threats. For the U.S. government to protect its much larger SSBN fleet, Tom Stefanick concludes, it must ensure “strong support for research in oceanography, sensors, and signal processing, as well as [for] SSBNs and their crews.”

Second, conclusions about technological trends are inherently uncertain and subject to rapid revision. While not the most likely outcome, rapid progress in AI or undersea drone technology could decisively empower anti-SSBN operations. Nuclear competitions have always been plagued by technological uncertainty. In the Cold War, Washington and Moscow both knew the other might limit its own vulnerability, a fear that drove them to build seemingly redundant forces to insulate their deterrents from technological shocks. The underlying fragilities in the nuclear balance became visible soon after the Soviet collapse; by the mid-2000s, the decay of Russia’s forces and warning systems and advances in U.S. counterforce combined to effectively dissolve MAD. For a number of years, Washington could have plausibly destroyed Moscow’s entire long-range arsenal in a “bolt-from-the-blue” attack, while Beijing might have been disarmed even if fully alerted.

Third, note that Russia’s willingness to risk nuclear war will depend on the perceived costs of war. From a bargaining perspective, the key variable for British decisionmakers is thus whether the Russian government believes it might be able to limit damage. If British officials think Moscow believes it can neutralise the UK’s sole patrolling SSBN, then in the short run they should behave as though MAD no longer holds, i.e. make larger concessions to avoid or restrain crises, even when certain it still does. Britain’s requirements for sustaining nuclear stalemate are thus more onerous—and Russia’s for undermining it are less onerous—than implied by analyses that cast beliefs about the military balance as necessarily accurate or symmetrical.

Fourth, reliance on a single patrolling submarine gives Britain’s national security a single point of failure, and although they remain extremely hard to track, a Vanguard-class submarine could be disabled by an accident or malfunction. Between 1988 and 2011, the Ministry of Defence recorded 14 collisions, mostly groundings, involving British SSBNs, along with 20 significant onboard fires. In 2009, HMS Vanguard collided with a French SSBN in the Atlantic; while neither was disabled, both suffered substantial damage. In 2023, the primary depth gauge on a Vanguard-class SSBN failed during a dive.

While unlikely, a severe incident could occur during an intense crisis; London would not disclose its impaired status, of course, but if it was revealed inadvertently, Moscow would perceive a fleeting first-strike capability. If Russian officials are already pessimistic about the course of the crisis, they might risk striking before the UK could “flush” an extra SSBN from Faslane. The flushing process might take several days even in an emergency, and the frenetic activity observable around the port could raise or confirm Moscow’s suspicions. 

Minimizing these risks is straightforward. Ideally, Britain would switch to dual patrols by constructing more than the four planned Dreadnought-class submarines. A fifth boat, as Andrew Futter emphasises, “would be relatively cost-effective given the economies of scale and sunk costs.” At a minimum, however, London should be able to rapidly flush a second boat in a crisis. The latter option is currently uncertain, and lengthening patrol times suggest growing strain across the overall maintenance cycle. 

In terms of maintenance and testing, Britain’s deterrent is highly reliant on cooperation with the U.S. The UK’s Trident missiles do not require foreign launch authorization, of course, but they are drawn from a joint U.S.-UK missile pool located in the United States. The decision to share missiles was taken in the 1980s under Thatcher, whose cabinet secretary described the prospect of Washington ever refusing to support the UK’s deterrent as “inconceivable.” Cooperation rests on the 1958 Mutual Defence Agreement, which was previously renewed each decade but then extended indefinitely in November 2024. Though certainly desirable, gaining full technological autonomy in strategic forces is not a top priority; no U.S. administration would exit the MDA short of a complete breakdown in Anglo-American relations.

Sub-strategic deterrence: The case for sovereign tactical nuclear forces

Given that nuclear stalemate remains in place, Britain has a range of options to enhance its military posture in a post-American Europe. 

Many analysts argue that a buildup of conventional forces sufficient to deny Russia any invasion capability in Eastern Europe is an essential deterrent requirement. As Chatham House’s Marion Messmer writes, “a visible and understood ability to be able to fight and win using conventional weapons is a vital piece of any deterrence strategy.”

However, a favorable local or global conventional balance is neither necessary nor sufficient to deter or prevail in crises involving nuclear-armed rivals. Under MAD, stronger conventional forces can indeed provide useful options at the lower end of escalation and prevent faits accomplis, as discussed below. But when neither state can defend itself from the other, crisis outcomes are ultimately determined by their comparative preparedness to escalate.

Russia’s leadership takes this logic for granted. As Michael Kofman and Anya Fink note, while “it does not write of nuclear escalation in recklessly optimistic terms,” the Russian military “expects a great-power war between nuclear peers to eventually involve nuclear weapons, and is comfortable with this reality... see[ing] escalation management as possible up to larger-scale employment.” Analysts generally agree; as Kofman emphasised in 2016, “Most Russian experts I know in the military analysis community, including those in Russia, don’t see much of a chance for conventional battle with NATO to stay conventional... [which] makes the [Western] debate over how many brigades to stick into the Baltics somewhat moot.” Accordingly, when Putin was asked in 2018 whether Russian security is threatened by the behavior of other states, he remarked that “we live in a world where security relies on nuclear capability. Russia is one of the largest nuclear powers… In this sense, we feel confident and calm.”

Although Russia’s nuclear-centric strategy is sometimes condemned as a leap into the Strangelovian unknown, it rests on the same concepts as NATO’s earlier approach. During the Cold War, NATO conventional forces were widely seen as unable to withstand a full-scale invasion of Western Europe. Accordingly, NATO’s deterrent posture rested on the threat to escalate a conventional clash to the nuclear level. Of course, Moscow’s ability to retaliate made an all-out nuclear response non-credible. Yet NATO’s strategy held that by employing limited nuclear options (LNOs), Western powers could present Moscow with risks far in excess of its potential gains, thereby deterring or halting a conventional attack.

In competitive risk-taking, the key variable is a state’s relative “resolve” or willingness to escalate, which is a function of the perceived interests at stake. Note that in this essay, we make the strong assumption that the British government values preserving the territorial status quo in Eastern Europe more than Moscow values revising it. What matters in practice, however, is not a state’s hypothetical willingness to escalate—a more or less pure function of perceived stake—but its willingness and ability to do so. The logic is straightforward: for an escalatory act to be rational, the expected costs cannot exceed the costs of backing down. Thus, even a highly resolute nuclear power which lacks limited options could face what Tyler Bowen terms a “resolve-capability gap,” forcing it to back down rather than over-escalate. Under MAD, the basic purpose of tactical nuclear weapons and conventional forces is to close credibility gaps in a state’s overall posture.

Russia, of course, possesses a wide array of LNOs. It currently maintains a tactical nuclear arsenal of around 2000 warheads arrayed on air, ground, and sea-based platforms, one that likely includes both reduced-fallout and “ultra low-yield” devices of around 10 tons of TNT-equivalent, comparable to the U.S. GBU-43/B conventional munition employed against Islamic State tunnels in Afghanistan in 2017. 

In stark contrast, the UK’s low-yield weapons were decommissioned after the Cold War. Trident SLBMs may be fired individually, but any launch would reveal the SSBN’s location; while an adversary would struggle to promptly destroy it, as rapid dives sharply dampen the effect of surface nuclear detonations, London’s uncertainty about the boat’s immunity from tracking might markedly increase.

For Britain to translate its resolve into coercive leverage will require more than a minimum deterrent. As Keir Lieber and Daryl Press emphasise, nuclear arsenals geared toward bargaining and conventional deterrence must be large, survivable (both in peacetime and across an ongoing conventional war), and flexible enough to facilitate selective use. The ultimate countervalue threat ought to remain feasible under all eventualities, while lower-level options should vary—in terms of provocation and costs imposed—from initial demonstrative use up to significant attacks. Such attacks would crucially avoid striking the adversary’s core population centers, so as to leave its incentives for restraint at least partially intact. The basic point is that Britain, as Kofman and Anya Fink write of the United States, “needs to develop its own strategy for escalation management, and a stronger comfort level with the realities of nuclear war.”

Commentators who oppose the acquisition of tactical nuclear weapons often characterise such a move as self-defeating, since the adversary would simply respond with a buildup of its own. A Liberal Democrats’ policy document, for example, calls for ruling out tactical nuclear arming, which it describes as “primarily designed to provide for battlefield advantage as opposed to having a deterrence purpose,” due to “the potential for a tactical nuclear weapon arms race.”

However, because Russia already maintains a large tactical nuclear arsenal, a British buildup should not provoke countervailing arming. Tactical weapons are not designed to alter the overall military balance, which remains stalemated under MAD, but rather to provide limited-use options. Relative force size is thus essentially irrelevant beyond low levels. The flip side is that if Russia were to respond by expanding its tactical arsenal, the deterrent benefits of the British buildup would remain and UK security would not be threatened, provided the new tactical balance does not jeopardise the country’s assured-destruction capability.

Many senior officials acknowledge that Britain’s lack of viable LNOs places it at a major disadvantage. Admiral Tony Radakin, the country’s recently retired armed forces chief, reportedly views tactical nuclear arming as Britain’s number one defence priority, while the head of Britain’s Civil Service from 2020 to 2024, Simon Case, is a convinced proponent. But a major decision on acquisition has yet to be taken. 

At the 2025 NATO Summit, Prime Minister Keir Starmer announced the planned purchase of twelve American F-35A fighters capable of carrying B-61 Mk. 12 nuclear bombs with a yield that can be adjusted from 0.3kt—less than the force of the 2020 Beirut explosion—up to 50kt, a move that will allow Britain to participate in NATO’s “nuclear sharing” of American B-61s. It was described in the official press release as “the biggest strengthening of the UK’s nuclear posture in a generation,” one that “reintroduces a nuclear role for the Royal Air Force for the first time since the UK retired its sovereign air-launched nuclear weapons following the end of the Cold War,” thus “strengthening NATO’s nuclear deterrence posture.” A Wall Street Journal article similarly referred to the move as an “overhaul of Britain’s nuclear policy.”

However, Britain’s participation in nuclear sharing cannot provide effective LNOs nor plausibly enhance NATO’s tactical deterrent. Without American authorization, B61-12s remain physically inert, and while Washington could greenlight tactical use in a future crisis, it would be an American decision, and perceived as such, presumably taken regardless of whether a portion of the U.S. arsenal were carried by European rather than American aircraft. Accordingly, despite the language of the press release, Defence Procurement minister Maria Eagle later clarified that the government was “not seeking to widen our range of nuclear capability” and the F-35A “is not some kind of stepping stone to acquiring tactical nuclear weapons.”

For Britain, the proper “stepping stone” may be the development of warheads for either a new air-launched cruise missile (ALCM) or an existing system such as Storm Shadow. Any such project would be costly, but ought to be prioritized, if necessary at the expense of broad investments in conventional forces. Fortunately, an important enabler for tactical options, the ability to suppress and destroy Russian integrated air defence systems (IADS), would also be a high-return conventional investment. Russian IADS have gained extensive experience against Western weapons since 2022, and in a conventional conflict, could shield ground forces from oncoming fires and thus largely neutralise Europe’s tactical air power advantage. Following escalation to the nuclear level, Russia’s air defence bubble could prevent limited use by Britain or France.

Other conventional capabilities also matter; most importantly, the local conventional balance should not be so skewed as to enable Russia to present Western powers with a fait accompli. If Russian forces could seize territory covered by Article 5 without encountering major resistance, the onus for triggering a large-scale conflict which might turn nuclear would shift onto European capitals, and rather than take that risk, NATO might accept the loss. Russia’s essentially bloodless seizure of Crimea in 2014 is a classic fait accompli, and similar scenarios were discussed by Western analysts during the Cold War, when NATO forces were postured to defeat limited aggression in West Germany.

Fortunately, raising a “thick tripwire” against Russian faits accomplis is unlikely to require massive conventional balancing by European powers. In combination, British, French, German and Polish forces are probably capable of blunting a Russian ground attack, though they lack the mobility to surge eastward at pace. Force requirements are of course relative; following a ceasefire in Ukraine, Russia could seek to build up much larger peacetime conventional forces, so that preserving a safe imbalance would require a proportionally greater buildup by NATO states. Given the conventional capabilities that satisfied Moscow before its invasion of Ukraine, however, this would entail a marked shift in either aims or threat perceptions. 

Finally, to improve and indeed maintain its military position in Europe, Britain will have to invest in the massed drone systems and counter-drone capabilities being relentlessly innovated by Ukrainian and Russian forces across widening “kill zones” between their lines of contact. Fully autonomous drones will remain largely absent in the short term, but European powers are far behind both belligerents in drone production capacity and continue to treat small UAVs as specialised assets rather than shell-like expendables. A successful production and innovation effort would also facilitate large transfers to Ukrainian forces.

Conclusion

This essay has argued that outright U.S. disengagement from Europe is now plausible, and outlined the main military preconditions for Britain to adopt a much more independent grand strategy in Europe. These preconditions should not be confused with the country’s overall military requirements, which depend on a much broader set of judgements, notably which non-security interests are to be forcefully defended in the absence of an American security umbrella and how much risk the country should run to protect its interests. Any sound overall approach to foreign affairs, however, takes the requirements of grand strategy as its point of departure.

Alex Hughes