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China's nuclear expansion challenges European security by complicating NATO’s deterrence posture, raising concerns about extended deterrence and necessitating a strategic recalibration by NATO nuclear powers.

Many observers of European security still assume that China’s nuclear arsenal build-up does not threaten European interests. Yet as China moves away from a minimalist nuclear force posture, the US must necessarily recalibrate its own strategy and posture. This has a grave bearing on NATO’s deterrence construct, in which nearly all European allies depend on US nuclear weapons to provide for their fundamental security needs. China’s nuclear expansion thus adds urgency to the need to adapt NATO’s nuclear posture to the post-2022 environment.

China’s emergence as the second nuclear peer competitor of the US cannot help but impact European security in three ways. Firstly, it raises new questions for all three NATO nuclear powers as far as their nuclear strategy and posture are concerned. Washington, London and Paris face the question of whether their legacy posture remains fit for purpose in the future. If not, they will probably recalibrate their posture accordingly. Secondly, the emergence of nuclear multipolarity complicates deterrence decision-making and signalling. This may well translate into an erosion of the confidence allies have in extended deterrence. Thirdly, China’s growing arsenal puts renewed emphasis on theatre-level (as opposed to strategic-level) nuclear deterrence. As such, developments in the Indo-Pacific region amplify the need to reinvigorate NATO’s theatre-level deterrence.

Instead of thinking about China’s nuclear arsenal as something that hardly affects European security, nuclear deterrence dynamics in Europe and the Indo-Pacific must be analysed together. With concerns about potential US abandonment already high in Europe due to the looming spectre of a second Trump presidency, China’s nuclear shadow can no longer be ignored by European capitals.

The Challenges to NATO’s Strategic Deterrence

China’s emergence as a nuclear superpower poses a challenge to the strategic nuclear forces that are the supreme guarantee of the security of all NATO allies. The construction of hundreds of new Chinese intercontinental ballistic missile silos, the ongoing switch to solid propellants, and the exercises of the People’s Liberation Army suggest that China is moving to a launch-on-warning posture akin to those maintained by Russia and the US. By the end of this decade, the Chinese arsenal is expected to grow beyond 1,000 operational nuclear warheads.

China’s posturing in its neighbourhood cannot help but impact extended deterrence in the NATO context because the US arsenal forms the backbone of the US-led alliance system worldwide

This raises different questions for NATO’s nuclear powers. Washington is already embroiled in an intense debate over the need to augment its nuclear modernisation plans. In turn, London and Paris face the question of whether their arsenals, which historically have been designed with the ability to strike Moscow as the benchmark, retain sufficient deterrence value under nuclear multipolarity. Even if the French and British targeting strategies do not depend on numerical parity, major changes to the balance in strategic nuclear weapons mean that London and Paris must re-evaluate the technical adequacy of their existing posture.

Washington has become quite familiar with the two nuclear peer problem. Early in 2023, a study group convened by the Center for Global Security Research at Lawrence Livermore National Laboratory analysed the implications of China’s emergence as a second nuclear peer in great detail. The final report of the bipartisan Strategic Posture Commission recommended significant changes to US nuclear deterrence in order to be capable of simultaneously deterring Moscow and Beijing. If the US government stays committed to its existing nuclear strategy of holding the adversary arsenal at risk, China’s nuclear breakout will necessitate growing the size and adapting the composition of the US arsenal.

Yet China’s growing nuclear arsenal also begs the question of whether France and the UK as separate centres of nuclear decision-making will respond with posture changes of their own. Against the background of the Ukraine war, both Paris and London have embraced wholescale nuclear modernisation, as explained by the French 2022 National Strategic Review and the UK’s Integrated Review Refresh of 2023. Will Paris and London remain satisfied with the deterrence value of their existing ability to exact vengeance in the event of an all-out conflict involving two opposing nuclear superpowers? Under such a scenario, a larger part of the US arsenal will be reserved for targets in the Indo-Pacific theatre instead of the European theatre. Whether London and Paris will step into the deterrence gap that would result from fewer US nuclear weapons being available for striking Russian targets remains to be seen. Yet growing doubts over what London and Paris consider ‘strict sufficiency’ may prompt changes to French and British stockpiles, plans and capabilities. Even if Paris and London would struggle to fully replace US-provided extended deterrence, they could mitigate their relative vulnerability to nuclear coercion by expanding their range of retaliatory options.

The UK Defence Nuclear Enterprise Command Paper released in March 2024 highlights China’s expanding numbers of nuclear warheads and delivery systems. Not only does it emphatically declare the nuclear deterrent to the defence of NATO, but it also speaks repeatedly about potential adversaries in the plural. One way in which the UK could step up is by reintroducing a second nuclear delivery system. Similarly, French President Emmanuel Macron has emphasised that nuclear deterrence is at the heart of French defence strategy and an element to be reckoned with in the defence of the European continent. After having declared US–China competition to be ‘an established strategic fact which … from now on will structure, all international relations’, Macron’s nuclear overtures presumably speak to the doubts some may have about US extended deterrence commitments.

Complicating Deterrence Decision-Making and Signalling

Discussions about nuclear posture adaptation reverberate strongly in the Nuclear Planning Group, the senior NATO body on nuclear matters. During the Cold War, such discussions had one single adversary as their referent. The logic of deterrence had a quasi-dyadic character. Yet today, China’s nuclear rise is vastly complicating deterrence signalling and decision-making. The larger number of actors cannot help but rob deterrence of its earlier simplicity. This has major consequences for NATO because the emerging strategic tripolarity threatens to erode the confidence allies have in the US ability to deter different threats simultaneously.

As all three NATO nuclear powers grapple with deterrence challenges emanating far away from the Euro-Atlantic area, the choices they make will be interpreted as deterrence signals by the leaderships of multiple adversaries. In turn, these may give rise to further choices in Moscow, Beijing and other capitals such as Pyongyang and Tehran. US posture changes meant to address the consequences of China’s growing arsenal may prompt Russia to take countermeasures of its own. China’s posturing in its neighbourhood cannot help but impact extended deterrence in the NATO context because the US arsenal forms the backbone of the US-led alliance system worldwide. Nuclear multipolarity could thus set unpredictable chain reactions into motion. This generates novel challenges for the Nuclear Planning Group, as NATO’s nuclear strategy can no longer be tailored to the Russian threat alone.

This emerging nuclear multipolarity has grave consequences for strategic stability. First, the interconnectedness between the Euro-Atlantic and Indo-Pacific theatres is set to increase. Every posture change or deterrence signal in response to China’s nuclear rise will prompt multiple assessments and responses by adversaries and allies alike. This is bound to fuel uncertainty rather than predictable nuclear equilibria. Second, such uncertainty may well prompt greater caution in the heads of key leaders, resulting in a desire to differentiate between strategic deterrence (in which the homeland offers a degree of sanctuary) and theatre-level deterrence (in which risk tolerance must be higher for the sake of extended deterrence). As nuclear deterrence is robbed of its earlier simplicity, strategic-level nuclear forces lose part of their value as instruments for providing extended deterrence. 

A Renewed Focus on Theatre-level Nuclear Deterrence

China’s nuclear expansion features the development of a theatre-level nuclear arsenal. This concerns foremost the Dong Feng-26 intermediate-range ballistic missile with a reported range of 4,000 km and a high degree of precision, characterised by the US Department of Defense as ‘the most likely weapon system to field low-yield warheads’. Another example is the introduction of the H-6N bomber, capable of delivering air-launched nuclear cruise missiles. These developments indicate that China has grasped the coercive value that theatre-level nuclear weapons can provide in a regional conflict.

In response to the combined nuclear threats from Russia and China, NATO’s nuclear posture will need to become more robust, more survivable and more diversified than it is today

Theatre-level nuclear weapons generate strike options that differentiate between a geographically limited regional war and a full-blown strategic nuclear exchange. By trying to create and exploit a gap between the US and its allies in terms of their relative vulnerability in a conflict, such systems allow China to leverage any theatre-level conventional superiority as well as to threaten nuclear escalation to stave off conventional defeat. In the NATO community, such a vocabulary is well-known in the context of Russian nuclear sabre-rattling. This now risks being repeated by a second adversary that is much stronger in conventional terms. With China acquiring a large, diversified and fully survivable nuclear arsenal, extended deterrence relationships in the Indo-Pacific region will require theatre-level nuclear weapons just as much as NATO needed them in the Cold War.

While this is particularly troubling for Indo-Pacific allies, the implications for NATO allies are equally hard to overstate. Firstly, these developments reverse the post-Cold War trend of deprioritising theatre-level nuclear weapons that many policymakers in European capitals still take for granted. Secondly, as nuclear multipolarity increases the risk of miscalculation, the extended deterrence value of strategic arsenals is set to diminish unless this devaluation is offset by an increase of theatre-level systems. Extended deterrence guarantees embodied by non-strategic weapons deployed in theatre are much stronger than the promise of strategic nuclear weapon employment that allies have no say over. Thirdly, as both Russia and China field larger numbers of theatre-level nuclear systems, severe stress is being put on the US arsenal of theatre-level weapons due to competing demands. Given the limited number of available B-61 bombs, the emerging requirements in the Indo-Pacific may call the cross-theatre distribution of theatre-level weapons into question. Moreover, the risk of overstretch associated with simultaneous regional crises pertains to all sorts of deterrence capabilities, not just nuclear ones. US Air Force bombers, for instance, constitute critical assets for suppressing enemy air defences and enabling nuclear operations in both the European and Indo-Pacific theatres.

Take-aways for NATO Nuclear Posture Adaptation

After the Nuclear Planning Group consultations in June 2023, then NATO Secretary General Jens Stoltenberg explained that ‘we continue to adapt our nuclear deterrence to the changing security environment’. While this comment related to the deployment of Russian nuclear weapons to Belarus, it is not hard to see that nuclear developments in the Indo-Pacific will intensify the debate on NATO nuclear posture adaptation. NATO’s legacy posture – relying on small numbers of dual-capable aircraft delivering gravity bombs – is already no longer fit for purpose when taking Russia’s nuclear intimidation into account. While the introduction of the F-35A will offer a boost to NATO’s nuclear-sharing arrangements, NATO remains at a disadvantage vis-à-vis the wide array of non-strategic nuclear options fielded by Russia.

As China’s growing arsenal results in a greater emphasis on theatre-level nuclear capabilities, developments in the Indo-Pacific will exacerbate existing shortfalls. In response to the combined nuclear threats from Russia and China, NATO’s nuclear posture will need to become more robust, more survivable and more diversified than it is today. At the Vilnius Summit, NATO leaders called for ‘updating planning to increase flexibility and adaptability of the Alliance’s nuclear forces’. This relates to the numbers of dual-capable aircraft, the associated network of air bases, and the European air forces flying nuclear deterrence as well as conventional support missions. The need for a second theatre-level weapon system – offering greater stand-off capability and survivability – is already apparent in the light of the Russian threat alone. Yet China’s nuclear expansion does contribute to the growing urgency thereof, precisely because so many of the key capabilities needed for shoring up extended deterrence in the European and Indo-Pacific theatres are in such short supply.

The views expressed in this Commentary are the author’s, and do not represent those of RUSI or any other institution.

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