How Britain and Germany could establish a sub-strategic nuclear deterrent
The Memorandum | No. 13.2026
The nuclear debate across the Euro-Atlantic has accelerated rapidly. The expiration of the New Strategic Arms Reduction Treaty (START) on 5th February 2026 removed the final remaining United States (US)-Russian strategic arms control agreement. This ended not only the last formal numerical limits on deployed strategic systems, but also the vital verification and risk-reduction measures that accompanied them. Concurrently, Emmanuel Macron, President of France, gave a speech at Île Longue nuclear submarine base in March in which he signalled a more outward-facing French deterrent posture, unveiling a so-called ‘forward deterrence’ doctrine aimed at dispersing French strategic assets across the continent.
Together, these developments force a reckoning that many European governments had long preferred to avoid: as the strategic environment worsens and Washington is increasingly drawn towards the Western Hemisphere and Indo-Pacific, how should Europeans respond – especially in terms of nuclear deterrence?
Focusing on a novel supranational arsenal risks answering the wrong question. The answer lies not in a ‘Euro-nuke’ or new architectures designed to enable nuclear release. Rather, the real solution is to be found in the burgeoning British-German defence partnership. By building upon the Trinity House Agreement of October 2024 and the subsequent bilateral Kensington Treaty of June 2025, the United Kingdom (UK) and Germany are uniquely positioned to address the Euro-Atlantic’s most acute vulnerability: the lack of a sovereign, sub-strategic nuclear deterrent.
…while conventional European rearmament is vital, it is fundamentally insufficient to deter a nuclear-armed adversary such as Russia. The unique destructive power of nuclear weapons compels a level of adversarial caution that conventional deep-strike or cyber forces simply cannot match.
Washington’s pivot to the Indo-Pacific is no longer rhetorical. The reallocation of American naval assets to counter the People’s Republic of China (PRC) is monopolising the availability of Virginia class submarines, leaving the Greenland-Iceland-UK (GIUK) gap increasingly reliant on British and European assets. Additionally, in an Indo-Pacific contingency, the US nuclear umbrella over Europe may be found wanting.
This is fundamentally a question of American availability rather than reliability. The US no longer prepares for even a two-front war, and Washington has been explicit that Europeans must assume primary responsibility for the defence of their own continent.
However, while conventional European rearmament is vital, it is fundamentally insufficient to deter a nuclear-armed adversary such as Russia. The unique destructive power of nuclear weapons compels a level of adversarial caution that conventional deep-strike or cyber forces simply cannot match. This necessitates a specifically European-led sub-strategic nuclear response capability.
In parallel, the UK and Germany have deepened defence cooperation through the Trinity House Agreement and Kensington Treaty. Meanwhile, Britain’s commitment to purchasing additional F-35A Lightning II Joint Combat Aircraft and rejoining the North Atlantic Treaty Organisation’s (NATO) dual-capable aircraft nuclear mission marks a significant shift in posture, supplementing rather than replacing the Royal Navy’s Continuous At-Sea Deterrent (CASD).
Beyond the ‘Euro-nuke’: Sovereignty and capability gaps
The challenge is no longer whether European NATO members should think seriously about nuclear deterrence: they already are. The true difficulty lies in designing an architecture that genuinely strengthens Euro-Atlantic security rather than merely duplicating existing structures. A fully fledged ‘European deterrent’ – a so-called ‘Euro-nuke’ – is often discussed as a single, obvious destination, yet it is fraught with distinct geopolitical, legal, and capability hurdles.
NATO’s nuclear architecture is deeply entrenched, with Belgium, Germany, Italy, the Netherlands, and Turkey collectively hosting roughly 100 American gravity bombs. Unsurprisingly, many allies question the utility of building a parallel European umbrella rather than adapting this existing framework.
The fundamental hurdle, however, is credibility. Extended deterrence is structurally fragile; the Kremlin may calculate that London or Paris would simply not risk domestic annihilation to defend NATO’s eastern flank. This anxiety is compounded by the US National Defence Strategy, published in January 2026, which prioritises the Western Hemisphere and the Indo-Pacific, and mandates European conventional self-reliance. To prevent a European deterrent from being dismissed as a declaratory bluff, it must be underpinned by integrated command structures and verifiable operational planning.
However, the constraints facing Berlin, Warsaw, and other European capitals through their adherence to the Non-Proliferation Treaty (NPT) rules out the simple multiplication of new national deterrents without severe political consequences. It is equally unrealistic to expect London or Paris to surrender launch authority to a novel supranational body, such as a multilateral European nuclear security council: such a structure would struggle to move quickly in a crisis scenario.
As the NPT prohibits transfer of control, the constant requirement for consensus would collide with the need for immediate strategic signalling. While a smaller group – for example, the European Three (E3) of the UK, France, and Germany – could offer greater operational agility, excluding other frontline states – not least Poland – risks intra-alliance fragmentation. Nuclear decision-making is the ultimate expression of sovereignty, and must remain during a crisis. Any emerging architecture should therefore be built primarily around existing British and/or French forces.
Yet, these existing forces are currently undermined by specific capability gaps. The UK’s strategic deterrent remains formidable, with CASD maintained since 1969 and currently undergoing renewal as more sophisticated Dreadnought class nuclear-powered ballistic missile submarines (SSBNs) start to replace the ageing Vanguard fleet. France also wields a credible strategic force, increasing its stockpile of nuclear warheads for the first time since the Cold War to maintain ‘assured destructive power’. It also retains an air-delivered nuclear component.
But the two arsenals are not interchangeable, and neither can independently provide the layered, calibrated, flexible deterrence historically guaranteed by the US. Britain’s principal vulnerability is the absence of a sovereign sub-strategic capability, while the French deterrent, although more flexible, remains functionally decoupled from NATO’s integrated nuclear planning frameworks.
…without a European NATO nuclear power explicitly committed and able to wield sub-strategic nuclear capabilities, a gap exists which an emboldened Kremlin may seek to exploit in the event of a crisis wherein the US is unable to intervene.
This distinction matters because the core nuclear problem in Europe is not simply a matter of warhead counts; it is about credibility across the escalatory ladder. European strategic nuclear arsenals deter the gravest threats, but they may lack utility in fast-moving crises below the threshold of national survival.
Russia, conversely, possesses a range of sub-strategic nuclear systems and a doctrine designed to exploit ambiguity. Indeed, without a European NATO nuclear power explicitly committed and able to wield sub-strategic nuclear capabilities, a gap exists which an emboldened Kremlin may seek to exploit in the event of a crisis wherein the US is unable to intervene. If European governments are serious about a self-reliant posture, they must focus on the rungs of the ladder where gaps are most pronounced.
The British-German engine: Establishing a sub-strategic arsenal
The most practical route towards a European deterrent lies in complementing British and French strategic forces, rather than replacing them. The UK is central to this effort, possessing a capability no other European ally can easily replicate: an operationally independent strategic nuclear force assigned to NATO.
However, His Majesty’s (HM) Government should take the next step by rebuilding a British sub-strategic nuclear arsenal. Regenerating a sovereign sub-strategic capability would provide flexibility, close the asymmetry gap with Russia – the possessor of a wide array of nuclear forces at both the sub-strategic and strategic levels – reduce dependence on future US administrations, and reassure exposed allies.
This capability cannot and should not be pursued in isolation. Here, Germany is the indispensable partner. Berlin has the industrial and financial weight required to close the European capability gap in complex weapons production, and bilateral cooperation is already well established. A realistic division of labour would see the UK leading on warhead development and stewardship, while Germany and other willing allies finance and develop a sovereign, dual-capable delivery system, potentially linked to advanced deep strike programmes.
As per Trinity House, the two allies have already agreed to cooperate on developing an advanced deep-strike weapon. If this weapon is air-launched, the F-35A Lightning II Joint Combat Aircraft and the future Tempest airframe (which Germany may join) could then deploy the new missile. Such a missile could also be ‘dual-use’ – i.e., both nuclear and conventional – to save time and cost. This approach reduces duplication, operationalises existing bilateral frameworks, and creates a specifically European capability without breaching the non-proliferation regime.
Securing the architecture: Political coordination and air defence
If the military logic is to fill the escalatory ladder’s missing rungs, the political corollary must be to establish structured consultation among allies most exposed to Russian coercion. With Macron and Friedrich Merz, Chancellor of Germany, agreeing to establish a high-level French-German ‘nuclear steering group’ and include German conventional forces in French nuclear exercises, it is now over to the UK to reinforce European NATO’s emerging nuclear architecture.
A European caucus within NATO’s Nuclear Planning Group offers a viable forum. Rather than replacing NATO, it would allow Britain, Germany, France, Poland, the Nordic states, and others, to align deterrence messaging, exercises, and operational planning.
Additionally, deterrence requires robust defence. If the UK and Germany assume larger roles in this architecture, they must better protect the infrastructure upon which deterrence depends. Defending British nuclear bases, German air stations, and the wider Command and Control (C2) network through Integrated Air and Missile Defence (IAMD) complicates adversary calculations and strengthens both conventional and nuclear credibility. As defensive systems become more capable, they should be employed to protect key assets.
Greater bilateral coordination could enhance broader frameworks, such as the European Sky Shield Initiative, which relies heavily on seamless integration. HM Government’s 2025 Strategic Defence Review already places considerable emphasis on IAMD and on the Royal Air Force’s (RAF) role in this architecture. Now, it should be connected more explicitly to the emerging European nuclear debate.
This does not amount to a call for a wholly separate, supranational strategic deterrent, nor does it imply discarding NATO’s existing arrangements. The expiration of New START and the worsening geopolitical environment have fundamentally altered the Euro-Atlantic political landscape. If European governments are to harden the outer perimeter of NATO’s nuclear shelter, London and Berlin must take the lead in rebuilding the missing middle rungs of the escalatory ladder.
The most credible way forward is evolutionary rather than revolutionary. It is driven by a British-German engine: preserve British and French strategic deterrents, complement them with jointly developed nuclear sub-strategic options, and embed these mechanisms firmly within NATO rather than outside it.
James Rogers is Co-founder (Research) at the Council on Geostrategy.
This article is the result of a half-day conference held on 10th February 2026 with the kind support of the Konrad-Adenauer-Stiftung (KAS) UK and Ireland. This was the first in a series of events in 2026 that the Council on Geostrategy is organising in partnership with KAS to encourage closer defence cooperation between Britain and Germany.
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