French President Emmanuel Macron speaks in front of a Dassault Rafale fighter aircraft at Luxeuil-Saint-Sauveur Airbase in Saint-Sauveur, France, on March 18, 2025. LUDOVIC MARIN/POOL/AFP via Getty Images
France, UK must heed the call of Europe's new nuclear age
Paris and London can provide the assurances that stop a continental race for nuclear weapons, but it won't be easy.
French President Emmanuel Macron’s bold call to open a new “strategic debate” in Europe on the role of nuclear deterrence without the United States deserves commendation. Europe must be clear-eyed about the geopolitical tectonic shifts underway and their consequences. Chief among these is the idea that, given political tides in Washington, relying on the United States for the long haul is intolerable.
While little can be done overnight to replace the load-bearing role that the United States once played in European security, including with its nuclear weapons, Macron’s call should galvanize the continent’s capitals into an interrogation of the promises and limits of nuclear deterrence. As Europeans enter this new strategic debate, several questions will arise, and they won’t have simple answers.
Paris is contemplating a path the United States took at the start of the Cold War: “extending” its nuclear deterrence to European partners. To do this is challenging, primarily due to reasons of credibility. Denis Healey, a former British Minister of Defense, once quipped that while it “only takes a 5-percent credibility of American retaliation to deter an attack” from the Soviets, “it takes a 95-percent credibility to reassure the allies.”
This helps explain why the United States built the nuclear capabilities it did during the Cold War and why, to this day, it sees a role for a large, diverse nuclear arsenal. With the exception of Russia, which similarly fields a large arsenal, the seven other nuclear-armed countries—France included—have been able to rely on smaller arsenals because they’ve traditionally asked far less of theirs than the United States has.
Washington’s self-interest in extended deterrence was rooted in its broader preference for nonproliferation. By the 1960s, the United States had decided that it would prefer not to see nuclear weapons spread further, be it to friend or foe. To keep its friends non-nuclear—many of which were wealthy countries with capable scientific and technical enterprises that could sprint to the bomb if they so chose—it needed to render extended deterrence credible.
This meant basing nuclear weapons on European soil, setting up “software” within NATO to include allies in nuclear-policy discussions, and certifying allied pilots to deliver U.S. nuclear weapons with their own aircraft to share the burden of deterrence. All of this, over the years, helped address—if never perfectly defray—the credibility concerns that Healey alluded to.
Separately, the United States needed to answer the question that former French President Charles de Gaulle asked of John F. Kennedy: would the United States “be ready to trade New York for Paris”? Once the U.S. homeland could be attacked by Soviet intercontinental-range missiles, allies naturally wondered why the United States would be willing to run risks on their behalf.
De Gaulle was unpersuaded by Kennedy’s assurances, leading to France’s independent nuclear capability. Other allies chose to accept them. The U.S. decision to field a large nuclear force was, in part, designed to persuade its allies that it could plausibly limit damage against its own homeland by destroying many Soviet nuclear weapons before they might be launched. This so-called damage-limitation goal has been a central pillar of U.S. nuclear strategy ever since.
France and Britain’s nuclear forces, while they may provide psychological salve to a continent deeply disturbed by American abandonment, cannot provide similar practical assurances. But must they do so?
As Paris and London embark on answering the calls of Europe’s new, post-American nuclear age, they will need to consider these dilemmas—but they need not necessarily follow the American model. The French nuclear force, with just shy of 300 warheads, can wreak havoc on Russia or any other nuclear- or non-nuclear adversary that may challenge Paris’ vital interests. Its ability to meet European demands for credible deterrence may similarly be within reach.
For one thing, France—unlike Kennedy when challenged by De Gaulle—can make the case that its own vital interests are indivisible from that of the continent where it resides.
For another, France operates a somewhat diverse nuclear force, although substantially less so than that of the United States and certainly that of Russia. It possesses sea-based nuclear forces, designed to provide the ultimate secure second-strike capability. It also operates land-based aircraft that can launch nuclear-armed cruise missiles. This latter capability would provide Europe the path of least resistance to a more distributed substitute to what is today a limited American nuclear capability deployed to five NATO countries—four in Europe and Turkey. (France may also wish to consider reconstituting an intermediate-range ballistic missile force to lend its nuclear forces greater flexibility.)
Where France may usefully imbibe of the American experience is in the realm of “software.” As the United States has learned over decades, warheads and military kit are only part of the extended-deterrence equation. Software—in nuclear terms, this encompasses consultations, leader-level contacts, and alliance pageantry—all support the peacetime buttressing of solidarity and collective defense.
While adapting capabilities for Europe’s new nuclear age will take time, the work on software can begin much sooner with appropriate political will in Paris and other European capitals. Paris has been famously reluctant over the decades to engage with this very software—out of an interest in maintaining its own independence—so moving ahead will require an uncomfortable readjustment in French nuclear thought.
Separately, as it embarks on a deeper rethink of its nuclear relationship to the rest of Europe, Paris should considerably deepen the scope of its nuclear-weapons cooperation with the United Kingdom. The fundamental motivating purpose of such cooperation should be to reduce the UK’s substantial and fundamental dependence on the United States’ nuclear enterprise for the Trident missiles on board its four nuclear-armed ballistic missile submarines, which comprise the entirety of its force. It is not an exaggeration to say that, under current plans, London will find itself depending on the goodwill of Trump and his “America First” heirs if it is to sustain its nuclear deterrent into the remainder of the 21st century.
Paris and London already cooperate on various aspects of their nuclear-weapons stockpiles. Deeper cooperation would suit Paris’ objectives by reducing the longer-term burdens on France while ensuring that London can contribute to longer-term demands for European security by providing an alternative locus of decision-making and control for nuclear weapons.
This bilateral cooperation should be ambitious and should include joint exploration of the feasibility of reconfiguring UK submarines to accept French-made missiles, and the possible establishment of a joint enterprise to explore new, nonstrategic nuclear capabilities to render new forms of extended deterrence on the continent more credible in the face of a Russian nuclear arsenal comprising some 2,000 such weapons.
These are just the initial considerations as Europe embarks on a wholesale rethink of its security and defense architecture. There are other matters for Paris and other capitals to consider, such as how such adjustments could be made without doing fatal harm to the broader nuclear nonproliferation architecture.
States outside of Europe might well see such shifts on the continent as harbingers of a more dangerous world, but they should consider that, absent these shifts, the alternatives could be far more harmful for international security. Without Paris and London stepping up, European states may be prone to look to their own nuclear capabilities, unleashing a new era of dangerous proliferation.