British–German Nuclear Cooperation: Joint Support, Not Financing

In August, reporting by The Telegraph suggested Germany was considering offering financial support for the UK’s nuclear deterrent, as Berlin looks for ways to shore up European security. The extent and detail of any discussion along these lines remains unclear. Indeed, subsequently the German government explicitl denied talks over financing the Trident programme were taking place. Nevertheless, the broader question raised by the reporting is a real one. Germany and France have already begun a more structured dialogue on nuclear deterrence, while German officials and experts have periodically floated closer German involvement with the British and French deterrents.

Direct German financial contributions to the production and maintenance of the UK’s nuclear warheads or their delivery systems would be difficult to justify and could create more problems than they would solve. But this should not become an argument against closer Anglo-German cooperation on deterrence. There are other forms of burden-sharing and, more importantly, opportunities for closer coordination of nuclear and conventional deterrence that could strengthen the security of both countries and NATO.

A Costly Enterprise

At first glance, an offer of German financial support might appear tempting. The UK’s Defence Investment Plan commits more than £63 billion over the next four years to the wider nuclear enterprise, encompassing Dreadnought, the SSN-AUKUS programme, the replacement warhead and other nuclear-related activity. This is broader than the deterrent itself – SSN-AUKUS, for example, will produce conventionally armed submarines – but it illustrates the scale of the burden associated with maintaining the UK’s defence nuclear infrastructure.

The Dreadnought programme, which will deliver four new ballistic-missile submarines to replace the Vanguard class, has a budget of £31 billion, alongside a £10 billion contingency. The government has separately committed £15 billion during this Parliament to the sovereign warhead programme, encompassing development of the replacement warhead as well as sustaining the existing stockpile and modernising supporting infrastructure. The UK is also participating in the US programme to extend the life of the Trident II D5 missile.

Maintaining the UK’s deterrent is therefore expensive, particularly as the conventional demands on British and European defence are also increasing. Russia poses a growing military threat to Europe, while Washington increasingly expects European allies to assume a greater share of the burden of their own defence. In 2024–25 the Defence Nuclear Enterprise accounted for 18% of the defence budget; the Ministry of Defence expected this to rise to around 20% in 2025–26 and potentially as high as 25% in subsequent years. The ageing Vanguard fleet has meanwhile been required to sustain exceptionally demanding patrol cycles as the UK preserves continuous at-sea deterrence. Any future decision to add a sovereign sub-strategic nuclear capability would impose further demands on an already expensive enterprise. Even though nuclear spending is ringfenced within the MoD budget, the overall defence resource envelope is finite. Money and skilled personnel devoted to the nuclear enterprise ultimately cannot be treated as entirely separate from the wider challenge of rebuilding conventional forces.

Challenges of Direct Financing

German financial contributions might therefore appear attractive. Yet direct funding of British warheads or their delivery systems would be a poor form of burden-sharing.

The problem is not that German money would somehow give Berlin a formal veto over the use of British nuclear weapons. The Telegraph reporting itself suggested that Germany would not seek launch authority, and the UK would retain independent operational control. Rather, foreign funding could create uncertainty about the political conditions under which the deterrent could be sustained and developed over time. A meaningful German contribution would almost inevitably generate expectations of consultation over the capability it helped finance. It could also expose part of the programme to decisions by future German governments and parliaments.

This matters because the political independence of the deterrent has long been an important feature of British nuclear policy. Concerns about preserving national control were one factor in British scepticism towards some of the multilateral nuclear arrangements proposed during the 1960s. Today, the UK already relies heavily on cooperation with the United States, most obviously through its use of the US-produced Trident II D5 missile. This relationship has repeatedly generated claims that the British deterrent is not genuinely independent, even though the decision to use British nuclear weapons remains under British political authority. Creating an additional financial dependency would give critics a further basis for questioning the durability of that independence.

Yet rejecting this model should not mean rejecting closer cooperation with Germany on deterrence. Non-nuclear European allies are increasingly looking to the British and French nuclear deterrents to play a greater role in their security. The UK’s nuclear deterrent is already committed to the defence of Europe through NATO, with UK nuclear weapons integrated into NATO’s nuclear plans. NATO Allies therefore already benefit directly from the UK’s nuclear deterrent and are able to input into Alliance nuclear planning through the Nuclear Planning Group (NPG). However, there is clear demand to strengthen the credibility of UK nuclear assurances to allies. Closer cooperation with Germany could help the UK better meet growing expectations.

Alternative Arrangements

The most important gap in the European deterrent architecture as currently constituted is its lack of flexibility. Russia enjoys a massive advantage in tactical and theatre nuclear weapons and the spectre of transatlantic decoupling in the face of attacks on Europe which do not directly threaten the US has loomed large since the Cold War. While the US’ extended deterrent architecture continues to help manage that risk, there is a paucity of truly European flexible deterrence options, should the US nuclear umbrella start to fray.

Closer UK–German deterrence cooperation could help address this. One aspect of this is the ongoing UK–German collaboration on conventional deep strike capabilities. Jointly developed missiles with ranges of over 2,000km will be able to strike strategically sensitive targets within Russia (for instance, non-strategic dual-capable delivery systems and supporting infrastructure) without crossing the nuclear threshold. This would provide a strategically commensurate response to Russian tactical nuclear weapons use, leaving Russia with the choice of whether to escalate further and risk crossing a red line which would make the use of Europe’s strategic nuclear deterrents plausible. In effect, the ability to invert the ‘suicide or surrender dilemma’ would be a valuable contribution to European deterrence. Investment in such conventional capabilities would thus mean that NATO would not be required to match Russia weapon for weapon at the nuclear level.

However, there are ways in which this cooperation on advanced conventional strike could be deepened further. For example, the possibility of jointly developing a torpedo tube-launched version of the FC/ASW (Future Cruise/Anti-Ship Weapon) cruise missile for Germany’s Type 212 diesel-electric submarine would in effect transform a tactical platform into a strategic one from a Russian standpoint – not least because from positions in the Baltic an SLCM (submarine-launched cruise missile) would offer very low warning times. The adaptation of a cruise missile for submarine launch is complex but has been achieved with Russia’s 3M-14 Kalibr, which can be torpedo tube-launched from the Kilo class. German participation in the Global Combat Air Programme (GCAP) might also, in theory, contribute to Europe’s independent capacity to strike at depths which hold at risk targets the Russians deem strategic; however, this remains a longer-term endeavour and would require overcoming German reservations over the extent of their role in the platform design. Range is a key driver for the GCAP design and the platform could in theory carry a cruise missile such as Stratus, providing a capability analogous – though not quite identical – to a strategic bomber.

Integrated Deterrence

But these capabilities will only strengthen deterrence if their conventional and nuclear effects are planned coherently. NATO will therefore need to manage the balance between imposing strategically useful but controlled costs through attacks on high-value targets, and avoiding targeting capabilities which are of such importance to Russian nuclear forces as to make attacking them excessively escalatory. The issue is therefore not simply the acquisition of longer-range missiles. It is the political and military architecture governing how they are employed.

NATO possesses well-developed mechanisms for nuclear consultation through the Nuclear Planning Group, while conventional operational planning for strikes is conducted through the air component command. NATO itself increasingly emphasises the need for greater integration and coherence across the spectrum of conflict. Yet the emergence of large European inventories of strategic-range conventional weapons raises questions that sit awkwardly between these structures: which weapons should be transferred to operational commanders during a conflict and which should require additional political authorisation, and how conventional strikes should be coordinated with nuclear signalling and other instruments of escalation management? While risk mitigation is already built into allied targeting, the organisational architecture to enable risk manipulation is arguably not. France’s refusal to join the NPG and to participate in NATO nuclear planning and exercises further complicates efforts to effectively integrate nuclear and conventional operational planning.

Anglo-German cooperation could make a useful contribution here. Rather than creating a mechanism to finance the British nuclear arsenal, London and Berlin should use their existing defence relationship to develop common principles for the control and employment of strategic conventional weapons. These could subsequently inform a broader NATO framework connecting conventional strike planning more explicitly with the Alliance’s nuclear planning machinery. The Franco-German Nuclear Steering Group already points in this direction by bringing conventional strike, missile defence and nuclear deterrence into the same strategic conversation. Meanwhile, the Franco-British Nuclear Steering Group is meant to serve as a forum for nuclear coordination between London and Paris and could offer a bridging mechanism between French strategic and operational thinking and NATO nuclear planning.

The establishment of a formalised British-German integrated deterrence steering group, possibly as an extension of the Trinity House Agreement and subsequent Kensington Treaty, could help bring these various conversations together. Equally, a trilateral Franco-British-German forum could be considered. By setting its mandate to focus on integrated deterrence specifically – rather than just on nuclear or conventional planning – it can avoid accusations of duplicating or weakening NATO arrangements and instead supplement existing frameworks.

As such, whether or not a German offer to make financial contributions to the UK’s nuclear deterrent was actually extended, the reporting points to both growing expectations, among non-nuclear allies, of the UK nuclear deterrent’s contribution to European security and to options for closer UK integration into a shifting European nuclear deterrence architecture. Any openings to expand that conversation with Berlin should be given serious consideration.

© RUSI, 2026.

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