The rise of China as a nuclear peer to the US, amid deepening strategic ties with Russia, poses an unprecedented 'two-peer challenge' to NATO. Adérito Vicente examines how this shifting landscape endangers alliance cohesion. Here, he argues for a fundamental rethinking of Europe’s deterrence and defence posture
The global nuclear order is changing. China’s emergence as a second nuclear peer to the United States, alongside Russia’s strategic alignment, marks an unprecedented challenge. US nuclear policy, once designed for a bipolar rivalry with Moscow, must now contend with a two-front nuclear dynamic, intensified by the 2022 'friendship without limits' partnership between Beijing and Moscow.
For the US, this 'two-peer challenge' involves deterring or defeating aggression by Russia and China. This could manifest either as a collaborative effort or as opportunistic aggression, sequential attacks across distinct theatres: Europe and the Indo-Pacific. This scenario forces a re-evaluation of how alliances allocate resources, prioritise threats, and plan for mobilisation and synchronisation.
Amid full-scale war against Ukraine, Russia is brandishing its nuclear arsenal, lowering thresholds for nuclear use. In its 2024 revised nuclear doctrine, Moscow allows nuclear strikes even in response to non-nuclear threats. Its modernisation includes new intercontinental ballistic missiles, submarines, hypersonic weapons, and tactical deployments in Belarus.
Moscow allows nuclear strikes even in response to non-nuclear threats; China’s nuclear arsenal is increasing rapidly, casting uncertainty on Beijing’s true nuclear intentions
Concurrently, China’s nuclear arsenal is undergoing a rapid expansion. It will increase from an estimated 600 warheads today to a projected 1,500 by 2035. Despite its official ‘no first use’ doctrine, the buildup of 320 new missile silos creates 'quantitative ambiguity'. This casts uncertainty on Beijing’s true nuclear intentions.
The result is a tripolar nuclear world in which the US, Russia, and China upend the bilateral logic that underpinned Cold War-era strategic stability. This 'three-body problem' complicates nuclear doctrinal calculations, and undermines key defunct arms control treaties such as the Intermediate-Range Nuclear Forces and Anti-Ballistic Missile treaties. With New START set to expire in 2026, decades of disarmament progress risk unravelling amid a changing landscape of great-power nuclear competition.
However, the recent Alaska Summit between Trump and Putin, followed by potential negotiations, aims to promote peace in Russia’s war against Ukraine — and could signal a game-changing moment. If these diplomatic efforts succeed, they may open a window of opportunity to reinvigorate arms control and disarmament initiatives between Washington and Moscow.
Simultaneously, emerging technologies blur the lines between nuclear and conventional warfare. This further compromises second-strike credibility and command-and-control capabilities. Such an increasingly complex environment demands a fundamental rethinking of US deterrence to preserve strategic stability in an unstable and rapidly evolving nuclear order.
But the two-peer nuclear challenge is also a NATO and European concern. Russia’s 'escalate-to-deescalate' strategy and lowered nuclear threshold, paired with China’s opaque buildup and ambiguous no-first-use policy, create a dangerously unpredictable escalation dynamic. Moscow and Beijing are deepening military coordination. They have conducted over 100 joint exercises in the past 15 years. NATO can no longer count on either acting alone — or predictably.
Russia’s 'escalate-to-deescalate' strategy and lowered nuclear threshold, paired with China’s opaque buildup and ambiguous no-first-use policy, create a dangerously unpredictable escalation dynamic
Since its founding, NATO has relied on American nuclear forces to underpin its collective defence. But in a tripolar nuclear environment, extended deterrence faces unprecedented strain. If China provokes a crisis over Taiwan, could Russia exploit it in Europe? Would US commitments stretch too thin?
As Washington continues its strategic pivot toward the Indo-Pacific, concerns in Europe deepen. This is amplifying doubts among allies about America's commitment to their defence. Poland, feeling exposed to Russian nuclear intimidation, is a vocal proponent of European nuclear cooperation.
NATO’s nuclear posture — anchored in US weapons as well as the independent arsenals of the UK and France — demands renewed scrutiny. Are these arrangements still adequate to deter aggression in a changed threat environment? Or is it time for Europe to close the credibility gap by assuming a greater share of the nuclear deterrence burden?
The 2025 Northwood Declaration between the UK and France signals progress in European nuclear cooperation. It reaffirmed that any extreme threat to Europe would be met by their nuclear forces. It also introduced concrete steps such as joint submarine patrols and enhanced nuclear consultation. Most notably, it established a UK-France Nuclear Steering Group to align policy, capabilities, and operations.
Since the inception of its nuclear weapons programme in the late 1950s, France has defended the principle of national independence over its nuclear forces. The Northwood Declaration, therefore, represents a potential shift toward greater coordination in European deterrence policy.
Yet challenges persist. The UK and France’s combined nuclear stockpile — over 515 warheads — pales in comparison with Russia’s estimated 5,459. For a joint Anglo-French nuclear umbrella to credibly protect Europe, both nations would need to signal a willingness to risk their own cities in defence of other European capitals. This level of security guarantee and reassurance remains difficult outside NATO’s established collective security framework.
Here, the concept of 'reasonable sufficiency' is key. Europe does not need to match American or Russian arsenals. Instead, its most credible path forward lies in anchoring its nuclear deterrent within NATO. This would reinforce the European pillar and complement — rather than replace — US extended deterrence. Coupled with sustained investment in advanced conventional forces, this strategy remains Europe’s most credible defence against Russia.
The 'two-peer nuclear challenge' marks a fundamental shift in global security, requiring NATO and its European members to adopt a coordinated, multidimensional strategy. This is not merely about nuclear numbers but about adapting to a more complex and volatile strategic environment.
NATO and its European members must adopt a coordinated, multidimensional strategy to cope with today's volatile strategic environment
First, NATO must sustain a credible and flexible deterrence posture by modernising US nuclear forces, upgrading dual-capable systems, and strengthening nuclear sharing arrangements to remain effective against two adversaries. Second, Europe must deepen its own security contributions; perhaps in the form of a 'NATO Europe'. The Northwood Declaration serves as a vital model for enhanced coordination and burden-sharing within the NATO framework. But it requires deeper investment in military and intelligence capabilities. Third, the erosion of arms control underscores the need for renewed focus on risk reduction efforts such as verification technologies.
As the world navigates the strategic complexity of a tripolar nuclear order, will Europe finally reinforce its nuclear deterrence — or will it remain a pawn in a game of global chess?
