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On February 20, 2025, shortly before Germany’s snap elections, Friedrich Merz, chairman of the conservative Christian Democratic Union and Germany’s next chancellor, made a prominent declaration about the future of European nuclear deterrence: “We need to have discussions with both the British and the French—the two European nuclear powers—about whether nuclear sharing, or at least nuclear security from the UK and France, could also apply to us.” Germany has been a key participant in NATO’s nuclear sharing arrangement since the Cold War, hosting U.S. nuclear weapons and maintaining dual-capable aircraft that could deliver them if necessary. This role has long been a symbol of transatlantic solidarity, yet it has become the subject of renewed political debate amid growing uncertainty over U.S. commitments to NATO’s security guarantees.
Q1: How is uncertainty over U.S. commitment shaping the European nuclear deterrence debate?
A1: Following Merz’s comments in an interview on Saturday, March 1, 2025, French President Emmanuel Macron said he was ready to “open the discussion” on European deterrence and recalled that “there has always been a European dimension to France’s vital interests within its nuclear doctrine.” Nevertheless, he made it clear that such a sensitive discussion would have to be carefully framed in the current strategic context where the U.S. political commitment might be questioned.
President Macron and Chancellor Merz’s remarks come at a pivotal moment, as U.S. President Donald Trump’s stance on NATO and his approach to Russia’s war in Ukraine cast doubt on the future of transatlantic defense cooperation. When Trump stated in 2024, “I would encourage them [Russia] to do whatever the hell they want,” he hinted that Washington may no longer uphold its commitment to defend all NATO members in the event of an attack—a direct challenge to the alliance’s core principle of collective defense. Officials in the new U.S. administration have added to these concerns.
While Germany has long relied on U.S. extended nuclear deterrence, growing uncertainty over Washington’s commitments has sparked debate over whether France and the United Kingdom could provide a viable alternative. However, significant strategic, doctrinal, and logistical obstacles make such a shift difficult.
Q2: What is the political context of Merz’s remarks on Franco-British nuclear protection in the current geopolitical context?
A2: First, Friedrich Merz’s remarks must be understood in context to assess their significance and intent. He made these comments during a live broadcast interview, not as part of a carefully prepared policy statement. Rather than a formal policy shift, official document, or prepared campaign statement, his remarks were a spontaneous response in a town hall–like setting with the interviewer directly asking him about British and French nuclear sharing. Merz is also known for his impetuous style that he used in his career as a businessman.
This distinction is crucial, as it suggests that Merz’s statement may not have been a deliberate attempt to pressure the U.S. administration into clarifying its commitment to NATO’s extended nuclear deterrence. Instead, his comments may reflect preliminary thinking about potential alternatives if needed.
Merz’s remarks were framed around the assumption of U.S. disengagement from European security. In the lead-up to a second Trump administration, European discussions were dominated by hypotheticals and fears of abandonment. Now, that fear seems to have evolved into a reality of abandonment—with the key question being to what extent the United States will withdraw. Considering this context, Merz underscored the urgency for Europe to become more self-reliant. He warned that “Donald Trump will no longer unconditionally honor NATO’s mutual defense commitment” and urged that Europe must “now make every effort to at least be able to defend the European continent on its own.”
Merz might also have wanted to show contrast with the previous chancellor, Olaf Scholz, whose stance towards defense policies has been marked by cautiousness and, at times, a fear of escalation with Russia that created frictions with Paris and London.
As Merz assumes office in the coming months, it will become clearer whether his remarks signal a serious shift in Germany’s approach to extended nuclear deterrence—or simply a moment of political rhetoric in a heated campaign environment. Serious diplomatic discussions on a European deterrent for Germany have not yet begun, as Merz is occupied with forming a coalition government.
Q3: What are the intentions of the United States regarding its nuclear extended deterrence policy in Europe?
A3: U.S. commitment to extended nuclear deterrence in Europe is rooted in NATO’s Article V collective defense pledge, reinforced by political assurances by U.S. officials that nuclear weapons remain a core component of deterrence, with NATO itself describing allied nuclear forces as the “supreme guarantee” of the alliance’s security. However, these assurances are political rather than legally binding. As of now, there are no decisions made in Washington that reconsider its role in providing extended nuclear deterrence to NATO allies, including to Germany where it is stationing several warheads. Over the past few weeks, officials in the Trump administration have questioned several aspects of U.S. commitment to Europe, suggesting that Europe needs to do more for its own defense and that U.S. troops will likely be pulled out of the continent. Nevertheless, they have not questioned the existence and pursuit of the U.S. extended deterrence, including the several hundred U.S. nuclear weapons stationed in Europe since the 1950s. In the months leading up to the U.S. elections, U.S. experts on both sides of the political spectrum have advocated for the pursuit of extended deterrence as a pillar of U.S. strategic posture. Even experts who call for a prioritization of U.S. forces abroad have called for a strengthening of the nuclear mission in Europe to deter potential simultaneous attacks in the European and Asian theaters.
Despite this, the strategic messaging of “burden shifting” to Europeans has triggered fear among European states that the political commitment underpinning the U.S. nuclear umbrella may no longer be reliable. Such concerns have arisen from the Trump administration’s emphasis on reducing U.S. military involvement abroad, sparking uncertainty about the long-term viability of NATO’s security guarantees. While the United States continues to reaffirm its commitment to extended nuclear deterrence in public statements, the lack of clarity regarding its political resolve has left NATO members, especially those in Europe, questioning the future political credibility of deterrence.
So, U.S. intentions regarding its nuclear extended deterrence policy in Europe, are becoming more ambiguous. The critical question is whether the United States will continue to honor its nuclear security commitments under all circumstances, or if evolving political dynamics might lead to a more limited role for the United States in the future.
Q4: Could Franco-British nuclear protection serve as a viable solution in the event of a U.S. withdrawal from the European continent?
A4: In the current situation, the French and British nuclear forces are a complement to U.S. extended deterrence, but they would not constitute a viable solution in the event of an abrupt withdrawal of U.S. nuclear forces.
France and the United Kingdom do not provide an extended deterrence guarantee the way the United States does in NATO. The mere existence of these two independent nuclear allies is seen as an addition to U.S. strategic posture and extended deterrence in Europe that complicates an adversary’s calculations. This contribution of the two European nuclear-weapons states to the Atlantic alliance’s overall nuclear posture has been recognized since the Ottawa summit of 1974.
Nonetheless, the arsenal’s structures and nuclear doctrines of France and the United Kingdom make it unlikely that they would be willing and able to replace U.S. extended deterrence in the event of a complete withdrawal. First, the size of the French and British arsenals is strictly tailored to respond to an attack based on their vital interests. France, with less than 300 nuclear warheads, and the United Kingdom, with less than 250, have far smaller arsenals than the United States that possesses a total of 1,700 deployed warheads. Second, the nuclear weapons currently stored by the United States in Europe are airborne capabilities, as opposed to seaborne or ground-based systems. Out of the two European nuclear powers, only France owns an airborne nuclear component. Replacing the U.S. extended deterrent as it exists would require strenuous efforts on the part of European allies, which makes this perspective even more unlikely. Finally, and most importantly, the two European nuclear powers do not have nuclear doctrines that are compatible with the idea of extending their nuclear deterrence through stationing their weapons in other countries. The United Kingdom explicitly stipulates that its nuclear deterrent is already assigned to the defence of NATO. On the other hand, France does not participate in NATO’s nuclear planning group and has a nuclear doctrine that insists on the independence of its nuclear decisionmaking.
It should be noted, though, that Emmanuel Macron invited European partners to engage in a strategic dialogue with France on “the role played by France’s nuclear deterrence in [their] collective security” back in 2020, in a speech that outlined France’s nuclear strategy. This presidential offer was meant to provide space to discuss the “European dimension” of France’s vital interests. Four years later, European allies could seize this offer to prompt discussions on the role of France and the United Kingdom as the two European nuclear powers. This would have to be crafted carefully so these discussions would be relevant to the most pressing need on the European continent, which is to bolster conventional contributions to the overall defense posture. It would also be necessary to avoid sending any signal of defiance in extended deterrence that could be exploited by NATO’s adversaries to attempt to divide allies.
Q5: How would a shift in Europe’s nuclear posture impact the nonproliferation architecture?
A5: The impact of a shift in Europe’s nuclear posture on the nonproliferation architecture will depend on the nature of the change. The Treaty on the Non-Proliferation of Nuclear Weapons (NPT), which prohibits new countries from developing nuclear weapons and is the foundation of the global nuclear order, does not explicitly address NATO nuclear sharing, but the practice remains a point of debate. NATO members argue that nuclear sharing does not violate the NPT because the weapons remain under U.S. control in peacetime. They also contend that the practice was established before the treaty’s entry into force in 1970 and was explicitly taken into account and acknowledged during negotiations.
In an extreme scenario, such as stationing French or British nuclear weapons in Germany, the limits of the NPT would be stretched. While Germany would not receive direct control over the warheads, critics would argue that such a move violates the treaty—in spirit or even its articles more explicitly. Indeed, it would constitute a new nuclear sharing arrangement that was not provided for in the NPT and it could even be at odds with France and the United Kingdom’s obligations regarding disarmament if this new configuration required increasing the size of their nuclear arsenals. Russia recently tested these boundaries by deploying nuclear weapons to Belarus, sparking debate over the implications for the treaty.
Less drastic shifts, such as stationing French nuclear-armed aircraft in Germany or other European allies who would express their interest, might not directly challenge the nonproliferation regime but would likely feed criticisms, particularly amongst nonnuclear weapon States in the Global South, where double standards in the West’s approach to nuclear issues are prevalent. Moreover, with Russia openly defying international law and China criticizing U.S. nuclear extended deterrence in the Indo-Pacific, any change in Europe’s nuclear posture could augment strategic risks in an already tense geopolitical environment.
Such a move could trigger additional ripple effects. Other regional powers might see it as justification for strengthening their own extended deterrence arrangements—or even pursuing independent nuclear arsenals. Ukrainian President Volodymyr Zelensky has openly suggested that Ukraine could seek nuclear weapons if NATO membership remains out of reach. Officials in Saudi Arabia, South Korea, and Japan have made similar conditional statements about potential nuclear proliferation. Keeping allies from obtaining nuclear weapons has also long been a U.S. policy objective of extended deterrence.
Q6: How can European countries, such as Germany, engage relevant stakeholders in discussions on nuclear deterrence?
A6: To foster meaningful discussions on nuclear deterrence, Germany and other European countries could pursue a progressive and cautious approach involving dialogue with key transatlantic stakeholders.
First and foremost, it would be essential for Germany to engage with the United States within the NATO framework to request additional information on Washington’s strategy regarding extended deterrence. Germany could initiate conversations about how Washington sees its extended deterrence commitment in the medium to long term and how it can align with the broader U.S. deterrence strategy. Germany could also suggest addressing U.S. expectations regarding European involvement in reinforcing NATO’s conventional posture, which is important to ensure flexible response and ensure the nuclear threshold remains as high as possible. A more integrated approach can ensure that any adjustments to Europe’s nuclear posture are part of a broader strategic framework rather than reactive responses to shifting alliance dynamics.
Additionally, Germany and other willing countries in Europe could open bilateral dialogues with France and the United Kingdom regarding their nuclear contributions, building upon the French president’s 2020 offer for more communication amongst Europeans on nuclear deterrence. This dialogue could help clarify the roles that France and the United Kingdom play in the nuclear domain and how their deterrent capabilities complement or support the deterrence and defense posture of Europe. By making these contributions more explicit, Germany could help enhance solidarity within Europe and foster a sense of shared responsibility among NATO members. The goal would be to create greater cohesion and a stronger European voice on nuclear deterrence issues within the alliance.
Finally, it is crucial for Germany and all European states to raise public awareness about the importance of nuclear deterrence in Europe’s defense. While support for NATO’s nuclear mission has grown since Russia invaded Ukraine, stark geographical divides remain between East and West Germany. However, lasting improvements in defense policy require broad and sustained public backing. More engagements could involve public discussions, educational campaigns, and greater transparency regarding the role of nuclear weapons in maintaining peace and stability on the continent. By fostering a well-informed public, Germany could ensure that its citizens understand the necessity of nuclear deterrence, not only as a matter of national defense but as a vital part of Europe’s collective security framework. This awareness is critical for building political will and public support for a robust and coherent nuclear strategy that is both credible and effective in protecting Europe from potential threats.
Astrid Chevreuil is a visiting fellow with the Europe, Russia, and Eurasia Program at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Doreen Horschig is a fellow with the Project on Nuclear Issues at CSIS.
