Introduction

Europe's security environment has dramatically changed since Russia's war against Ukraine, persistent nuclear coercion by Moscow and growing uncertainty surrounding the future role of the US in European security have reignited debate about the role of nuclear deterrence on the continent. Russia's full-scale invasion of Ukraine in 2022 demonstrated that large-scale interstate war remains a reality in Europe, while Moscow's repeated nuclear threats have highlighted the continued importance of nuclear weapons as tools of coercion and strategic influence. At the same time, uncertainty over the long-term reliability of US security guarantees has increased. Concerns about the future of transatlantic relations, combined with Washington's growing strategic focus on the Indo-Pacific, have raised questions about the extent to which the US will continue to underpin Europe's conventional and nuclear deterrence posture. These developments have prompted concerns that Europe needs to assume greater responsibility for its own security, either because US commitments weaken or because Washington becomes less willing to bear the primary burden of extended nuclear deterrence. In this context, France has sought to expand the European dimension of its independent nuclear deterrent while maintaining exclusive national control over nuclear decision-making. In March 2026, President Emmanuel Macron announced a new concept of 'forward deterrence', aimed at deepening strategic dialogue and practical cooperation with European partners. The initiative reflects a broader French effort to foster a shared European strategic culture and strengthen Europe's capacity to act in an increasingly contested security environment.

NATO nuclear deterrence

Europe is currently undergoing the most significant transformation of its nuclear posture since the end of the Cold War. After three decades during which the role of nuclear weapons steadily declined within European security policy, concerns about strategic instability, Russian aggression and the long-term reliability of transatlantic security guarantees have returned nuclear deterrence to the centre of defence planning. While the overall number of nuclear weapons deployed in Europe remains far below Cold War levels, NATO member states are investing heavily in modernisation programmes, infrastructure upgrades, operational readiness and nuclear planning mechanisms to ensure that deterrence remains credible.

NATO defines itself as a nuclear alliance and views nuclear weapons as a core component of its broader deterrence and defence posture alongside conventional forces, missile defence, cyber capabilities and space assets. The alliance maintains that the primary purpose of nuclear weapons is to preserve peace, prevent coercion and deter aggression. The 2022 NATO strategic concept states: 'NATO will take all necessary steps to ensure the credibility, effectiveness, safety and security of the nuclear deterrent mission. The Alliance is committed to ensuring greater integration and coherence of capabilities and activities across all domains and the spectrum of conflict, while reaffirming the unique and distinct role of nuclear deterrence'. Political control over nuclear policy remains highly centralised through the Nuclear Planning Group (NPG), NATO's principal body for consultation and decision-making on nuclear matters. Through the NPG, all NATO members – with the exception of France – participate in discussions on nuclear strategy, force posture, exercises and deterrence policy, reinforcing the principle that nuclear deterrence remains a collective alliance responsibility rather than the exclusive domain of the nuclear-armed states. France, the UK and the US are NATO's three nuclear-weapon states under the Non‑Proliferation Treaty. While the US provides the core of NATO's nuclear deterrent, the independent nuclear forces of the UK and France also contribute to the alliance's security. France does not participate in NATO's nuclear arrangements, including the NPG, because since the presidency of Charles de Gaulle it has maintained a doctrine of strategic autonomy, insisting that its nuclear forces must remain under exclusive national control and outside multinational command structures.

A central pillar of NATO's deterrence architecture is the nuclear-sharing arrangement. By distributing both the political responsibilities and operational risks associated with nuclear deterrence, these arrangements reinforce alliance solidarity and cohesion. They also provide participating allies with a role in shaping NATO's nuclear policy and posture that they would otherwise not possess. From an operational perspective, nuclear sharing offers both military and political instruments for deterrence and can contribute to escalation management during crises. Moreover, nuclear sharing serves as the clearest manifestation of the US's extended deterrence commitment to its European allies and contributes to limiting incentives for nuclear proliferation across Europe.

In practical terms, NATO's nuclear-sharing arrangements mean that participating allies share not only the benefits of US extended deterrence, but also its political responsibilities and operational risks. They participate in nuclear decision-making through NATO's NPG, contribute dual-capable aircraft, personnel and infrastructure to support NATO's nuclear mission, and, if authorised, could deliver US nuclear weapons in a conflict. In return, they accept that these assets and bases could become priority targets in a crisis or war, reinforcing alliance solidarity and burden sharing. A NATO nuclear mission involving US nuclear weapons requires political consultation and approval within the NATO NPG, but the release and use of the weapons ultimately requires authorisation from the US president.

According to the Bulletin of the Atomic Scientists, the US Air Force is estimated to deploy between 100 and 120 B61‑12 non‑strategic nuclear weapons in Europe under this arrangement. (Strategic nuclear weapons are designed to deter or conduct large-scale nuclear war by targeting an adversary's homeland, leadership or nuclear forces; non‑strategic (tactical) nuclear weapons are intended for battlefield or regional use and provide more limited options for deterrence and escalation management during a conflict.) These weapons have long been stationed at six air bases across five NATO member states: Aviano and Ghedi in Italy, Incirlik in Türkiye, Kleine Brogel in Belgium, Volkel in the Netherlands and Büchel in Germany. Their deployment is embedded within NATO's nuclear-sharing framework, under which dual-capable aircraft operated by host nations are certified and equipped to deliver US nuclear weapons, if authorised. Although Greece and Türkiye previously maintained additional nuclear weapons storage facilities, the weapons assigned to these sites have since been removed, leaving the storage vaults in a caretaker status. Consequently, Greek and Turkish F‑16 aircraft now retain only a residual contingency role within NATO's nuclear mission.

Source: Bulletin of the Atomic Scientists, December 2025.

NATO's nuclear arrangements are currently being modernised. This is centred on two major developments: the introduction of the B61‑12 gravity bomb and the transition to the F‑35A Lightning II fighter aircraft. The B61‑12 represents a significant technological improvement over earlier variants, incorporating enhanced guidance and accuracy that increase operational flexibility and effectiveness. Simultaneously, NATO members are replacing ageing Tornado and F‑16 aircraft with dual-capable F‑35As able to carry both conventional and nuclear weapons. The introduction of new aircraft and weapons systems has required extensive infrastructure modernisation across Europe. Air bases involved in the nuclear mission are undergoing substantial upgrades to weapons storage facilities, security systems, command-and-control networks, aircraft shelters, maintenance facilities and communications infrastructure.

Alongside force modernisation, NATO has also increased its emphasis on nuclear readiness and training. The annual 'steadfast noon' exercise remains the alliance's principal nuclear training activity, involving dual-capable aircraft from numerous member states. Although no live nuclear weapons are used, the exercise rehearses operational procedures, interoperability and coordination between conventional and nuclear forces. These activities demonstrate that NATO's nuclear posture relies on contributions from a much wider group of allies than those physically hosting nuclear weapons.

The UK and France's nuclear deterrence

The UK and France are western Europe's two nuclear weapon states, together maintaining an estimated stockpile of around 515 nuclear warheads in 2025 (according to the Bulletin of the Atomic Scientists, the UK had around 225 and France around 290 warheads ). France also has around 80 retired warheads pending dismantlement, bringing its overall nuclear inventory to roughly 370 warheads. While both countries operate independent nuclear deterrents under exclusive national political control, their relationship with NATO differs significantly. The UK assigns its nuclear forces to NATO's collective deterrence, whereas France remains outside NATO's nuclear-sharing arrangements, although its nuclear forces are recognised as making a significant contribution to the alliance's overall security. For comparison, the US and Russia maintain by far the world's largest nuclear arsenals. According to the Bulletin of the Atomic Scientists, the US possessed an estimated stockpile of approximately 3 700 nuclear warheads in 2025, with around 1 770 deployed, while Russia is estimated to have approximately 4 309 nuclear warheads assigned to its strategic and non‑strategic nuclear forces. Both countries are undertaking extensive nuclear modernisation programmes, although Russia currently maintains a larger active stockpile.

The French 'forward deterrence' initiative

In his March 2026 speech at Île Longue on France's nuclear deterrence, President Macron argued that Europe now faces a far more dangerous security environment, characterised by Russian aggression, growing nuclear proliferation, uncertainty about long-term US security guarantees and the erosion of arms control regimes. In response, he announced a strengthening of France's nuclear deterrent, including an increase in the number of nuclear warheads, greater opacity regarding arsenal size and the continued modernisation of France's strategic nuclear forces.

The central innovation of the speech was the introduction of a policy of 'forward deterrence', which seeks to deepen nuclear cooperation with European partners while preserving France's complete sovereignty over nuclear decision-making. Macron proposed regular strategic consultations, allied participation in French nuclear exercises and the potential temporary deployment of elements of France's strategic air forces to allied territory. However, he explicitly rejected any sharing of nuclear decision-making, planning or the definition of France's vital interests, stressing that the initiative does not constitute a formal nuclear guarantee or replacement for NATO's nuclear mission.

Macron presented forward deterrence as complementary to NATO and linked it to stronger European conventional capabilities, particularly in missile warning, air and missile defence, and long-range strike systems. More broadly, he argued that Europeans must assume greater responsibility for their own security and work towards a new European security architecture adapted to an era of renewed great-power competition and heightened nuclear risk.

The French proposal represents an attempt to 'Europeanise' deterrence without Europeanising ownership or control of nuclear capabilities. Rather than replicating NATO's nuclear-sharing arrangements, it seeks to create greater European involvement in the political and strategic dimensions of deterrence. The initiative aims to strengthen consultation on nuclear issues, improve understanding of escalation dynamics and encourage European contributions to supporting capabilities such as early warning systems, integrated air and missile defence, and long-range precision strike. France increasingly argues that its vital interests possess an inherently European dimension because of the continent's deep political, economic and security interdependence.

NATO's nuclear-sharing arrangements are based on the forward deployment of US nuclear weapons in Europe, with participating allies hosting US B61 bombs, maintaining dual-capable aircraft and participating in nuclear planning through the NATO NPG. Although the weapons remain under exclusive US control until a decision on their use is authorised by the US president, participating allies share the political responsibilities and operational risks associated with NATO's nuclear mission. By contrast, based on current information, President Emmanuel Macron's initiative does not seek to establish a European equivalent of NATO nuclear sharing. Instead, it proposes a strategic dialogue on how France's independent nuclear deterrent could contribute to European security, while preserving France's long-standing principle of exclusive national control over its nuclear arsenal and remaining outside NATO's nuclear-sharing arrangements.

Several European countries have joined discussions with France on deterrence-related cooperation, including Germany, Poland, Sweden, Denmark, Belgium, Greece, the Netherlands and the UK. In May 2026, Norway became the latest participant. The decision is notable given Norway's traditionally strong Atlanticist orientation and reliance on NATO's collective defence arrangements. While Oslo reaffirmed that NATO remains the cornerstone of its security policy, its participation suggests growing interest among European states in complementing existing deterrence structures through closer engagement with France.

In June 2026, Finland's parliament voted to lift its long-standing ban on facilitating NATO nuclear weapons on its territory. The reform reflects Helsinki's post‑2022 shift in security policy following Russia's invasion of Ukraine, while the government is also exploring closer cooperation with France's proposed European nuclear deterrence initiative, although no final decision has been taken.

Lithuania is debating the removal of its constitutional ban on nuclear weapons. The country's parliamentary parties reached a political agreement in July 2026 to pursue a constitutional amendment. The proposed reform represents a major legal overhaul and would require approval by a two-thirds majority in two separate parliamentary votes. President Gitanas Nausėda emphasised that there are no immediate plans to host nuclear weapons, but that removing the restriction would give Lithuania and NATO greater flexibility should the security situation worsen.

Across the emerging debate on France's new policy of forward deterrence, analysts broadly agree that it represents a significant adaptation of French nuclear policy to a deteriorating European security environment, but not the creation of a European nuclear umbrella. Jyri Lavikainen of the Finnish Institute of International Affairs argues that the initiative strengthens NATO's deterrence posture by enabling the dispersal of French nuclear-capable aircraft to allied territory and increasing allied participation in French nuclear exercises. However, because France has retained its traditional doctrine of central deterrence and rejected a flexible response posture, the policy does not constitute an alternative to US extended deterrence and should instead be understood as a complementary addition to NATO's existing deterrence architecture.

Similarly, Héloïse Fayet of the French Institute of International Relations (IFRI) contends that Macron's concept of forward deterrence seeks to integrate France's nuclear forces more closely into European security while preserving the core principles of French nuclear doctrine and strategic autonomy. Although the initiative expands consultation and cooperation with European allies, including the potential deployment of French nuclear-capable aircraft during crises, it stops short of offering formal security guarantees and is intended to complement rather than replace NATO and the US nuclear guarantee. Michel Duclos of Institut Montaigne likewise views Macron's March 2026 speech as an important evolution of French nuclear policy, driven by a worsening security environment and growing uncertainty. While he emphasises that forward deterrence remains complementary to NATO, Duclos argues that it outlines a roadmap for strengthening both European deterrence and conventional defence cooperation. He further suggests that the initiative implicitly prepares a potential fallback option for some European states should US extended deterrence weaken in the future. Claude-France Arnould of the Brussels Institute for Geopolitics also interprets forward deterrence as a pragmatic adaptation of France's long-standing deterrence doctrine. In her view, the initiative operationalises the European dimension of French nuclear policy through deeper cooperation with selected European partners, helping to reassure allies and strengthen European security amid uncertainty over US guarantees. Nevertheless, like the other analysts, Arnould stresses that the policy does not amount to the establishment of a formal French nuclear umbrella for Europe.

European Parliament position

In its resolution of 21 January 2026 on the implementation of the 2025 annual common security and defence policy report, Parliament recognises that nuclear deterrence remains an important component of European security, noting that France and the UK are the only European states possessing nuclear weapons, and stating that a nuclear deterrent is of crucial importance for the protection of Europe. The European Parliament also expresses concern about the weakening of non‑proliferation and arms control regimes, and calls for the EU to take on a stronger role in preventing the spread of weapons of mass destruction. It reaffirms support for the Treaty on the Non‑Proliferation of Nuclear Weapons as the cornerstone of global non‑proliferation efforts, while recognising the importance of nuclear deterrence for European security. The Parliament also urges greater transparency and coordination in EU arms export policies, and calls on Member States to apply EU export control rules strictly, particularly where there is a risk that exported weapons could be used for aggression.