What if the United States decided to fold up its nuclear umbrella over Europe? In its wake, Europe could either experience increased Russian aggression, potentially threatening the very existence of the European Union, or a wave of nuclear proliferation that would severely challenge the international nonproliferation order. However, relying more substantially on existing nuclear capabilities on the continent — particularly France’s nuclear arsenal — could help prevent both. Yet even observers that do not in principle oppose the idea of a French umbrella have raised concerns about its viability. Most commonly, these concerns question the authority to use nuclear weapons, France’s willingness to defend its allies if deterrence fails, and the overall size of the French nuclear arsenal. While these concerns are valid, they exaggerate the challenge. In fact, similar uncertainties exist regarding the U.S. nuclear umbrella and should therefore not be considered major hurdles.
For starters, the U.S. president retains final decision-making power over nuclear use. Although NATO has a consultation mechanism through the Nuclear Planning Group, it is unlikely that the United States would condition its nuclear decisions on alliance-wide consensus. Any NATO decision would ultimately be non-binding because only the U.S. president has ultimate decision-making authority about nuclear weapons. Similarly, the French President holds sole authority over France’s nuclear weapons, which are not currently included in NATO’s nuclear consultations, as France is not a member of the Nuclear Planning Group. However, there is no reason why France could not adopt a similar approach to that of the United States, agreeing to inform and consult with its allies in peacetime, while maintaining final authority over nuclear use. Potentially, such a consultative body could be purely European, aligning with France’s longstanding goal of strategic autonomy. Moreover, it is far from guaranteed that Washington would come to Europe’s defense in a crisis. Compared to the United States, France’s geographic proximity and economic interdependence with its European allies should provide an advantage when it comes to resolve. However, to enhance their arsenal’s size and flexibility, Europeans will need to develop robust solutions. Greater emphasis on the airborne component of the French deterrent will likely be essential, although this need not require deployments abroad. Among other options, these solutions could include creating a low-yield variant of existing capabilities. Importantly, a funding mechanism would be required to share the financial burden. This could take the form of direct financial contributions — such as creating a novel funding institution by a coalition of the willing — or by cross-financing the French deterrent by offsetting costs in emerging areas of European defense cooperation, such as the Future Combat Air System. In addition, while a U.K. contribution to a European nuclear umbrella would encounter challenges like those faced by France, along with some unique to the United Kingdom, it could serve as a valuable complement to the French umbrella.
The Great Withdrawal
Europe has awakened to the new reality of U.S. withdrawal. Recently, President Donald Trump attacked his Ukrainian counterpart and insisted that he would only protect those allies that pay an ever-increasing share of their GDP on defense. However, Europe had already begun adjusting. By 2024, before Trump took office, 23 of NATO’s 32 members met the 2 percent GDP defense spending goal — up from just 6 members in 2021. In March 2025, Europe further strengthened its defenses, with E.U. plans to offer €150 billion in defense loans to member states and Poland announcing to expand its army from 200,000 to 500,000 troops.
Yet, conventional deterrence can only take Europe so far. In fact, nuclear deterrence has been the backbone of NATO’s military strategy since the beginning of the Cold War. If Europeans no longer trust U.S. security guarantees to deter external aggression, they will need alternatives. In recent weeks, there have been renewed discussions about France’s nuclear role in Europe, including, for the first time, a strongly positive response from Germany. Meanwhile, Polish Prime Minister Donald Tusk made an ambivalent statement about the need for Poland to acquire the most modern weapons, explicitly mentioning nuclear weapons, while at the same time emphasizing that Poland would seek discussions with France.
Do Allies Need a Say in Nuclear Decision-making?
In recent months there has been a lively debate about deepening nuclear cooperation between France and the United Kingdom, as well as how the French nuclear arsenal could play a broader role in European defense. However, three criticisms frequently challenge the plausibility of a French nuclear umbrella.
The first concern is that France would never hand nuclear decision-making power to its allies. Particularly, the French president would always retain sole authority over nuclear use. This is certainly true. Yet, the same applies in the current NATO model, where the U.S. president retains the sole authority to use U.S. nuclear weapons. While NATO-sanctioned nuclear use requires the approval of the Nuclear Planning Group, the actual implications of this process remain ambiguous. For instance, it seems implausible that, in the event of a crisis, deliberations within NATO would dictate U.S. decisions on nuclear use. This is even less plausible when considering scenarios in which allies seek to push the United States toward nuclear use rather than restrain it. In fact, NATO’s history suggests that allies have often been skeptical of U.S. commitments to meaningfully consult with them. Even after the adoption of the Athens Guidelines in 1962 — which specified that the United States would consult allies on nuclear use “if time permits” — key allies such as the United Kingdom, Canada, and Germany sought separate bilateral agreements with Washington to ensure their voices were heard.
As important, whatever consultative mechanisms exist, they are ultimately non-binding. The U.S. president retains sole authority over the use of America’s nuclear weapons. Furthermore, only a portion of U.S. nuclear weapons are assigned to NATO, meaning that only these could be subject to any form of shared decision-making in the first place. Another factor is the stationing of nuclear weapons on allied territory. However, these make up only about five percent of America’s nuclear arsenal. Host states might have a de facto veto power, given that nuclear deployment would require allied military personnel and fighter jets. At the same time, since the introduction of Permissive Action Links in the 1960s, no decision to use U.S.-owned nuclear weapons can be made without explicit U.S. authorization.
France would not need to give up its ultimate nuclear authority if France wanted to extend a nuclear umbrella over E.U. member states and European NATO allies interested in such an offer. A consultation body could take shape — one that includes information-sharing, involvement in military planning, and potentially deliberation about nuclear use — giving allies a voice without granting them formal decision-making power. One possibility would be for France to join NATO’s existing Nuclear Planning Group, though it has long resisted doing so. Another option is the creation of an entirely new European body outside of NATO. Paris might be more receptive to the latter idea as it aligns with France’s long-held aspiration for strategic autonomy from U.S.-dominated military structures.
Capabilities and Resolve: Assessing Credibility
The second challenge has to do with doubts that France would “trade Paris for Tallinn.” This argument is puzzling. Washington and Tallinn are 7,000 km apart, separated by what Trump frequently refers to as a “big, beautiful ocean.” Beyond relative geographical proximity, France’s economic ties to Europe further reinforce its security interests. All its largest export markets and four of its five biggest import partners are E.U. members. There are few conceivable scenarios in which a threat to the stability of the European Union would not constitute a vital national interest for France.
The third oft stated challenge is that the French arsenal is insufficiently flexible and too small to provide extended deterrence. This is arguably the most valid concern. France currently has about 290 nuclear warheads all of which are actively deployed on delivery systems or maintained at high readiness. Combined with the United Kingdom — the other potential partner in a European nuclear umbrella — the European arsenal size is comparable to China’s. However, it is still far smaller than those of Russia or the United States. Moreover, since the dissolution of its land-based nuclear missiles in the 1990s, France relies exclusively on sea- and air-based deterrents, including mainland-based aircraft, carrier-based aircraft earmarked for use on the Charles de Gaulle, and submarine-launched ballistic missiles.
Deterrence is commonly understood as a combination of capabilities — the hard power a state brings to the table through its warheads, missiles, planes, military training, and technology — as well as resolve. Deterrence can include factors such as a state’s history in past crises, regime type, and, most importantly, the stakes it has in a given conflict. France has a stronger interest in the security of Europe than the United States, making its commitment arguably more credible in this respect.
This could be achieved through direct funding, such as novel financing mechanisms from a coalition of willing nations, or through indirect assistance, like easing France’s financial burdens in other areas. For example, Germany could choose to assume a larger share of the burden in developing joint projects, such as the French-German-Spanish Future Combat Air System program. Another possibility is that European states involved in expanding missile defense capabilities under the European Sky Shield Initiative could exempt France from financial contributions if it were to join the project in the future. Most likely, a combination of multiple initiatives would be needed, allowing states to cross-finance parts of France’s nuclear capabilities.
The debate remains open as to whether deterrence solutions should involve a numerical expansion of the French arsenal or the introduction of entirely new weapon systems. Although developing land-based missiles seems unnecessary and would likely take considerable time, a low-yield variant of the Air-sol moyenne portée air-launched cruise missile could address skepticism among European allies. Such a system would also be relatively straightforward to implement, unlike the development or entirely new classes of nuclear weapons and delivery vehicles. In addition, France is already developing a successor to its existing missile, which includes hypersonic capabilities and is expected to enter service by 2035.
A new air-based nuclear weapon could also facilitate the stationing of nuclear weapons abroad. However, there is little evidence to suggest that the foreign deployment of nuclear weapons is an essential component of a nuclear umbrella. First, nuclear weapons have been stationed in states that were not under a nuclear umbrella, such as U.S. deployments to Spain in the early Cold War and U.K. deployments to Singapore in the late 1960s. Second, the United States has credibly signaled its commitment to protect South Korea and Japan, despite not maintaining a foreign-deployed nuclear weapons presence in the region since the end of the Cold War. Lastly, a key role of forward-deployed nuclear weapons has been to bind the United States to distant regions. However, France is already deeply connected to is European neighbors through geography and economic interdependence, potentially reducing the need for such deployments.
The British Connection
While the United Kingdom remains a nuclear-capable state, focusing on France’s nuclear arsenal is essential for two reasons. First, President Emmanuel Macron has long advocated for European autonomy and a stronger European role in France’s nuclear strategy, aligning with the country’s historical push for European independence. In contrast, the United Kingdom maintains closer ties to the United States. Prime Minister Keir Starmer has taken a softer stance toward the Trump administration and refrained from following European counter-tariff policies. Structurally, Britain’s membership in the Five Eyes intelligence network and its 2016 vote to leave the European Union has made it the most U.S.-dependent state in Europe; these decisions raise doubts about its willingness to pivot toward a new security strategy. Most importantly, the United Kingdom depends on the United States for its nuclear arsenal, leasing submarine missiles and basing its warheads on U.S. designs. There are even indications of potential renewed U.S. nuclear deployments to British soil, as occurred during the Cold War.
Second, the United Kingdom’s nuclear arsenal is more limited than France’s. While their overall stockpiles are similar, only about half of the U.K.’s arsenal is available for immediate use. The United Kingdom relies exclusively on four Vanguard-class submarines armed with ballistic missiles, with only one at sea at any point in time. Maintaining even this minimal presence has proven challenging, making the British deterrent a last-resort case. Once its submarine launches a missile, it becomes vulnerable, leaving the United Kingdom without further nuclear options. This limits its capability beyond defending a state-ending attack. Additionally, failed missile tests have raised further doubts about the reliability of the U.K.’s arsenal.
This does not mean that there is no role for the United Kingdom in a future European nuclear umbrella. As a member of the Nuclear Planning Group, it has experience consulting with allies on nuclear matters and could help design a European mechanism. Although the United Kingdom’s small and inflexible arsenal makes its use beyond national survival unlikely, it can still play a role in deterrence as a high-impact, low-probability factor. In fact, NATO has long maintained that French and British nuclear forces complement U.S. capabilities by “complicating the calculations of potential adversaries.” The United Kingdom could serve a similar role in complementing a French umbrella. A more ambitious approach would involve deeper Franco-British nuclear cooperation, especially if the United Kingdom moves toward a more independent arsenal. However, such a shift can only be a long-term prospect.
What is the Alternative?
Taken together, concerns over the credibility of a French nuclear umbrella seem overstated, as many of the same issues apply to the U.S. nuclear umbrella. The U.S. president retains sole authority over nuclear use, despite NATO’s consultation mechanisms. Moreover, the United States is less dependent on the E.U. economy and, more importantly, is geographically distant from Europe. Thus, the fact that France has a greater stake in European security might offset some of the challenges posed by the relatively small size of its nuclear arsenal. However, arsenal size and flexibility remain pressing concerns. Solving these challenges will require a combination of creative policymaking — such as co-financing or cross-financing the French deterrent by European allies — and concrete efforts to strengthen and modernize the arsenal.
There is an additional concern: Given current U.S. diplomatic approaches, what are the alternatives? Credibility critically hinges on the perception that the security guarantor is committed to defending its allies. Which E.U. member states trust that Trump would meaningfully consult with allies and consider their input before deciding on nuclear use? The current U.S. administration’s threats to annex some allies and its forceful approach toward others cast doubt on the credibility of U.S. security guarantees. Under these circumstances, it could be more reasonable to rely on France for protection. It is of course possible that U.S. policy will return to a more collaborative approach toward allies in Europe in four years. Yet, Europeans would be foolish to bet their security on wishful thinking.
In the meantime, Polish Prime Minister Tusk has hinted at the possibility of a Polish nuclear weapon. In Germany, a recent op-ed in a prominent newspaper openly called for an explicit nuclear hedging strategy to ensure a pathway to the bomb in a worst case scenario. If such ideas were to translate into actual policy, they would alter the European security landscape and disrupt the international nonproliferation order far more dramatically than an extended French nuclear umbrella. However, a strengthened French deterrent could directly address the very concerns that fuel such increasingly radical proposals.
Alexander Sorg is a postdoctoral Stanton Nuclear Security Research Fellow at Harvard University’s Project on Managing the Atom. His research focuses on European security, NATO, and extended nuclear deterrence. He has published in International Studies Quarterly, the European Journal of International Security, the NATO Defense College Research Papers, and War on the Rocks. Alexander’s work has also appeared in The Economist as well as various German and Dutch newspapers.
Image: Staff Sgt. Alexander Cook via Wikimedia Commons
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