Ulrich Kühn
Head of the arms control and emerging technologies program at the Institute for Peace Research and Security Policy at the University of Hamburg
First, the more important question: should they? Russia is a menace, no doubt. U.S. President Donald Trump loathes Europe. In a couple of years, Russia could launch another attack beyond Ukraine. Once more, Moscow could leverage its nukes to blackmail European defenders. Deterring such contingency is necessary. But Europeans should focus on conventional forces that make any Russian land grab in Eastern Europe impossible in the first place. Nuclear deterrence comes second; and it already exists.
French and British forces can, with some modifications, serve as European backstop: with deeper cooperation, more British independence from America, some more limited options for substrategic escalation, and creative efforts to reassure non-nuclear Europeans.
All that will be quite expensive. Joint financing might be a way. But it should respect the stipulations of the Nuclear Nonproliferation Treaty. Europeans should neither seek to match Russian capabilities, nor aim to replicate the current U.S. arrangement. They should also not strive to build the EU bomb, and must prevent individual countries from pursuing their own nuclear weapon. And they need to focus on the main task: Build a serious conventional deterrent!
Michal Onderco
Professor of International Relations at Erasmus University Rotterdam
The question asked is deceivingly simple. Of course, European countries—wealthy, technologically advanced countries with an elevated threat perception—can build their own independent extended nuclear deterrence. But it will not be quick, easy, or cheap. The issue is not so much the technology—in fact, the French ASMP-A missile could be seen an equivalent replacement of the existing tactical nuclear weapons in Europe.
The problem lies more in the strategy, posture, and trust. To put it very bluntly, France has never thought about its nuclear weapons in the terms of escalation management— certainly not in terms of managing the conflict in Europe—but as the ultimate punishment for an invader. Therefore, the development of an independent European nuclear deterrent would require strategic changes, which would need to be accompanied by changes in posture and political trust-building to be believable.
And as Thomas Schelling taught us, trust is built by having a skin in the game: For instance, by having troops stationed in the Eastern flank. And this is where the costs will lie. So can Europeans build their own extended deterrent? Yes. But is it likely to happen in the short term? It’d surprise me, but perhaps the need will push them to do the unthinkable.
Héloïse Fayet
Research Fellow and Head of the Deterrence & Proliferation Research Program at the Institut Français des Relations Internationales
Forget the fantasy of a Eurobomb or a travelling nuclear suitcase between EU capitals. The real question is how to better leverage the existing arsenals of France and the UK in a Europe where Washington’s commitment is no longer a given. What happens if NATO allies can’t trust that the United States will trade Boston for Berlin?
The answer is not to mimic the American model with tactical nukes scattered across the continent. If Paris and London were to extend deterrence, it would be because their national security is inextricably tied to Europe’s stability. Any adaptation must reflect this.
For France, that could mean clarifying its vital interests and going beyond presidential speeches that require explaining to be correctly understood by allies—but without sharing nuclear decisionmaking or stationing warheads abroad. Those are currently a no-go for Paris. Conventional forces, missile defense, and deep precision strikes must also be part of the equation. Instead of obsessing over warhead numbers, why not start by reinforcing French deployments on NATO’s Eastern flank?
Even though the UK considers it already participates in European security through its nuclear contributions to NATO, London must American-proof its long-term nuclear future in case of diminished cooperation with the United States.
The time for pragmatic nuclear dialogue and political commitments is now.
Andrew Futter
Professor of International Politics at the University of Leicester
Finding new ways to extend the UK nuclear umbrella to European allies, and perhaps more importantly demonstrate deterrence credibility, is not going to be straightforward or something that can happen quickly.
Since the 1960s, UK nuclear weapons have been committed to the defense of NATO, and since 1998, this has been through four nuclear-powered submarines and a minimum stockpile of missiles and warheads. But today there are questions whether this is sufficient in a much-changed European security context, and potentially one with a far less reliable ally across the Atlantic.
The capacity to rapidly enhance UK nuclear capabilities is limited: It is possible that the warhead cap of “no more than 260” could be marginally increased or additional nuclear-armed submarines might be built and deployed in the 2030s. An additional nuclear delivery platform could be acquired from the United States or France, though it would require a new UK warhead, or the “air leg” could be reconstituted indigenously. None of these options is easy, cheap, or necessarily politically expedient for the current government. And developing new capabilities will likely take years, not weeks.
Adding to the challenge is the fact that massive investment in conventional forces will be essential to the broader UK and European deterrent posture, and to making any nuclear assurance more convincing.
James Acton
Co-Director of the Nuclear Policy Program at the Carnegie Endowment for International Peace
The vast disparity in size between the American nuclear arsenal and its British and French counterparts has led many European experts to question whether London and Paris have the capabilities needed to extend deterrence to the rest of the continent.
These concerns are largely misplaced. Once a nuclear-armed state has a survivable nuclear force and some capability to conduct limited nuclear strikes, more is not better. The sheer size of the United States’ nuclear stockpile may comfort—or, rather, may have comforted—Europeans, but it did not actually lead to more deterrence. In the event of American withdrawal, London and Paris might want some more redundancy but a build-up à l'américaine would not be needed.
The bigger problem will be credibility. Is it really believable for one state to wage a nuclear war that might lead to its own destruction in defense of an ally? In theory, France and the United Kingdom might find it easier than Washington to answer this question in the affirmative. After all, a Russian invasion of Europe would pose a more direct threat to them than the United States.
Ultimately, however, logic can only go so far here. Whether London and Paris can convince Moscow, their allies, and themselves that they are serious about extending deterrence will be an empirical issue.
James Cameron
Associate Professor at the Department of Archaeology, Conservation and History of the University of Oslo
The Trump administration’s wavering commitment to Europe’s security means that the continent should develop its own nuclear deterrent based on the arsenals of France and the United Kingdom.
President Trump’s questioning of the United States’ commitment to defend NATO, aggressive attitude toward NATO members, and his admiration for Vladimir Putin’s Russia have undermined the credibility of the U.S. commitment to risk nuclear war in the defense of Europe.
Able to assure the destruction of key cities in Russia, France, and the UK’s eight ballistic-missile submarines could serve as an effective deterrent of large-scale Russian nuclear-weapons use against Europe.
However, Paris and London would have to develop a more robust air-delivered arsenal, based on France’s existing force that could provide more substrategic options to deter Russia from using its extensive arsenal of nonstrategic nuclear weapons.
This deterrent would need to be supplemented by a significant conventional buildup from European allies, designed to mount a successful defense against Russian invasion without resort to nuclear weapons.
London and Paris would then not need to threaten to use nuclear weapons first and instead focus on deterring Russian nuclear use, in a scenario where Moscow is facing conventional defeat.
Paul van Hooft
Research Leader on Defense and Security at RAND Europe
The French and British nuclear arsenals can deter existential threats to Europe : Both have enough weapons to inflict unacceptable damage on Russia. The difficulties are with low- or medium-intensity Russian actions at the edges of NATO.
The United States has a larger and more flexible nuclear arsenal suited for escalation, but it also needs more options as a non-European power with less vital interests at stake. Credible European deterrence is therefore not a matter of finding and replacing U.S. capabilities with French and British ones.
Europeans do need more advanced conventional weapons like precision strike, fifth-generation airpower, and air and missile defense to strengthen their ability to deter-by-denial. Imposing costs for Russian conventional aggression during the act, rather than through nuclear punishment afterwards, also raises the nuclear threshold.
For European deterrence to work it is crucial that Russian leaders at no point believe they can hamstring deterrence by targeting a specific state. Decisionmaking in a multinational EU deterrent would be too unwieldy. But a third European nuclear power would add appropriate uncertainty to Russian calculations. A Polish deterrent would be highly credible, but the route there is unfortunately very dangerous.
The French and British deterrents, backed with serious conventional weapons to blunt Russian aggression, is the most sensible avenue for now.
Alexander Bollfrass
Head of Strategy, Technology and Arms Control at the International Institute for Strategic Studies
Yes, but each component of that project faces significant challenges and opportunity costs.
First, to deter, a nuclear arsenal must credibly threaten an adversary with unacceptable damage. Against Russia, which has the world’s largest arsenal and an appetite for nuclear risk-taking, this would require substantial warhead numbers, diverse and reliable delivery systems, and robust command-and-control.
Second, while collective Europe has the scientific and material preconditions to construct a modest starter arsenal within a decade, the costs would be immense. Beyond the budgetary costs, Europe would face international backlash for treaty violations. Europeans would also have to brace for sabotage and military strikes on the program, as well as find a place to test its warhead designs.
Governing a Eurobomb to credibly deter would-be aggressors would require new political structures. The European Union is not equipped to handle collective nuclear decisionmaking. NATO is, but it does not offer independence from the United States. Europeanizing and growing French nuclear forces is the most obvious starting point, but there is no indication France would yield sovereignty over its national arsenal.
In all, a European nuclear arsenal would be long on opportunity cost and short on credibility. Europe would get more deterrence from fielding conventional forces, especially precision long-range strike.
George Perkovich
Japan Chair for a World Without Nuclear Weapons, Senior Fellow at Carnegie Endowment for International Peace
The United Kingdom and France would be the most likely alternate providers of extended nuclear deterrence. However, the UK exited the European Union, hardly an indication of willingness or credibility as a provider of nuclear deterrence for Europeans. France could be more likely, as indicated by President Macron’s rhetoric about European security. However, France has long remained outside NATO’s Nuclear Planning Group, and neither the left nor the right in French politics appears likely to endorse being a nuclear security provider.
Alternatively, as recent comments from leaders indicate, Germany and Poland, the largest frontline NATO states, could seek to build their own nuclear deterrents. Setting aside whether these capabilities would then be extended on behalf of others, many questions arise. What fissile material would be used to produce nuclear weapons, from what sources, and over what time? Would this be done in violation of the Nuclear Nonproliferation Treaty, and if so, what would the implications of that be? If not, how? Would Russia be more indulgent of such programs than Israel has been toward Iran, Syria, Iraq, and other adversaries whose scientists and engineers have been assassinated and nuclear facilities sabotaged and/or militarily bombed? What sorts of missiles, aircraft, and/or submarines would be deployed to deliver the imagined weapons, and how would they be made to survive possible pre-emptive attack by Russia?
