France wants to extend its nuclear umbrella to Europe. But is Macron ready to trade Paris for Helsinki?

Europe’s reliance on US nuclear weapons has been at the heart of the transatlantic security relationship, and so has been the protection that the old continent gets from being part of the NATO alliance and its powerful Article 5. Now, the debate about nuclear deterrence for the European Union is back at the forefront, in part due to the prospects of a reticent United States under a possible second Trump presidency and a resurgent Russia increasingly threatening to use nuclear weapons.

NATO, as a nuclear alliance, relies heavily on US nuclear warheads stationed in Europe for its deterrence. The United Kingdom and France are Europe’s only nuclear powers: Although part of NATO, they maintain independent control over their own nuclear arsenals. In the past, the European Union has been reluctant—or incapable—of providing nuclear deterrence. But the uncertain security environment in Europe has recently led the Union to strengthen its previously neglected security pillar—and, with it, caused some political leaders to become more vocal about nuclear weapons.

In recent weeks, France’s President Emmanuel Macron, in his classic disrupting style, has openly called for debate in Europe over using his country’s nuclear capabilities to defend the continent. In Macron’s view the uncertainty over future US engagement in Europe is forcing the European Union to decide whether it needs a nuclear deterrent of its own—and suggests France may help with this. But it is not clear whether France would be willing—and capable—of extending its nuclear umbrella to the rest of the Union. For this to happen, France would need to address multiple issues, starting with explaining whether it would retain full decision-making over its arsenal, exploring the limitations of its current stockpile of nuclear weapons, and weighing the impact such a decision would have on NATO and its relations with the United States and its fellow EU member states.

Macron’s insistence. Since the United Kingdom’s withdrawal from the European Union in 2020‚—popularly known as “Brexit”—France has become the Union’s only country with nuclear weapons. France possesses approximately 290 nuclear weapons (the world’s fourth arsenal in terms of stockpiles warheads behind Russia, the United States, and China). Ever since French President Charles de Gaulle’s famous questioning of US nuclear assurances in 1961— which led France to develop its own nuclear deterrence force—France has historically seen itself as an independent force counterbalancing that of the United States in Europe. This spirit persists today: France still does not participate in NATO’s Nuclear Planning Group and remains one of the Western allies most in favor of nuclear deterrence. France’s independent deterrence strengthens NATO overall because it complicates the calculus of adversaries. Although nuclear deterrence has been a cornerstone of NATO’s deterrence posture, the same cannot be said of the European Union: Many member states remain uncertain about the role of nuclear weapons in defense planning.

The debate over the nuclear readiness of the EU is not new. Traditionally, the holdout to developing a so-called “Eurobomb” has been Germany. In recent years, a growing number of German policy makers have asked the previously unthinkable question of whether it should possess its own nuclear weapons. The German public remains unconvinced, however: Even after the Russian invasion of Ukraine, 90 percent of Germans still reject the idea of their country developing a nuclear weapons program and it seems unlikely the German public will dramatically pivot toward a Eurobomb. Traditionally neutral EU countries such as Ireland, Malta, and Austria are not likely to be willing to support the bomb either: All three are signatories to the Treaty on the Prohibition of Nuclear Weapons (TPNW), also known as the ban treaty, and would likely block any attempt to extend France’s nuclear arsenal to Europe.

As the continent develops its security pillar—through its “strategic compass,” defense industrial strategy, and the upcoming formalized command and control structure in 2025—the supranational bloc could benefit from French leadership on nuclear deterrence. Macron first put forward the idea in 2020, calling for a “strategic dialogue” on “the role of France’s nuclear deterrent in [Europe’s] collective security.”

But this dialogue never happened. In 2022, after the Russian invasion of Ukraine, France again raised this matter with Germany, saying that the offer to talk about nuclear weapons was still on the table, arguing that the French nuclear deterrent is a way to protect European interests. In late April, during a speech on the future of European security at the Sorbonne University, Macron doubled down on the need for debating nuclear weapons in Europe, improving the continent’s missile defenses, acquiring more long-range weapons, and vowing that France would do more for Europe’s defense. But despite being quite explicit about his vision of a Europe capable of ensuring its own nuclear deterrence, Macron’s comments lacked details over the practicality—and even the feasibility—of his proposal, as well as its potential implications for the European security environment.

Easier said than done. To move forward with his proposal, President Macron will need to answer at least three critical questions about the politics and logistics of a European-level nuclear weapon sharing arrangement. First, France will need to clarify whether it wants to retain full decision-making power over its nuclear arsenal. When Macron made his first comments in 2020, the idea was not about sharing the deterrent but rather that France would reserve the right to decide under what circumstances it would use its nuclear arsenal. However, with the changing global security environment—in particular, Europe’s situation  since 2022—Macron is now more urgently suggesting that there is a “European dimension to France’s vital interests.” He says he wants all European countries to put their capabilities in plain view, including stationed US nuclear weapons, as a show of force and to assert the credibility of European defense. French presidents in the past have maintained strategic ambiguity by not explicitly stating what they considered were the vital interests of France. Now Macron, more than any of his predecessors, emphasizes that the security of Europe and that of France are intimately connected.

Second, it is not clear how France could realistically provide nuclear deterrence to the entire Union. French nuclear forces have limited capabilities, with a much smaller and less diversified arsenal than that of other major nuclear powers, and its nuclear deterrence has been developed for a strictly defensive purpose. France partially disarmed its nuclear arsenal in the 1990s after the Cold War, reducing its nuclear stockpiles from 600 warheads to just under 300.

This figure is pegged to France’s perception of what it needs to defend itself and its territory. Were France’s nuclear capabilities to expand to cover the entire European Union with extended deterrence, the country would need to increase its stockpiled nuclear warheads considerably. However, as part of its partial disarmament of the 1990s and embracement of a doctrine of minimum deterrence, France dismantled its land-based nuclear defenses. France also closed test sites and fissile material production facilities, which would make it difficult to expand its warhead production capabilities.

Dramatically expanding the territory under its nuclear umbrella would also stretch the credibility of France’s own nuclear deterrence. Even if the country’s air- and sea-based nuclear arsenal would not necessarily need to be deployed to neighboring countries, the French president would have to decide the circumstances in which France could foresee using its nuclear capabilities to defend one or several of its fellow EU members. As de Gaulle famously asked Kennedy whether the United States would be ready to trade New York for Paris in the event of a nuclear attack, Macron too must ask himself whether he is willing to trade Paris for Helsinki.

In practice, the idea of a French nuclear umbrella for Europe also raises a third question for Macron: How to embed the French nuclear armament into existing European structures and how this shift would complement NATO’s capabilities in Europe. NATO’s Nuclear Planning Group would be fitting for discussions of strengthening European deterrence, but France is unlikely to agree to take part in the group as it seeks to also maintain its independence in nuclear decision-making. While the United States has pressed European allies to do more to provide for their own defense, the idea of a Eurobomb would likely raise some eyebrows in Washington: Many of the closest US allies among NATO countries in Europe, such as Poland and the Baltic states, would most certainly prefer the stability offered by continuing to rely on the US nuclear deterrence and reject any attempts by France to replace—or at best, complement—US nuclear presence in Europe.

A more isolationist US administration, however, could change that calculation among these European countries and propel France’s ambitions to provide nuclear deterrence to Europe by a considerable factor. Either way, the credibility of the European Union as an actor capable of providing for its own nuclear deterrence remains low considering the slow progress of the EU’s Common Security and Defense Policy. To get there, the Union would first have to start a more intensive nuclear dialogue.

France could also begin to win over some of its EU partners by hosting nuclear deterrence exercises, including fostering cooperation between EU member states on nuclear issues and sharing processes with one another. Such exchanges could help improve military cooperation between NATO and EU members, thereby advancing the development of a European strategic culture while working on protecting European interests. To play a stronger role in providing nuclear deterrence to Europe, France could also base part of its airborne arsenal in other EU member states, agree to share its arsenal to be carried by fighter-bombers of other European countries, or some combination of the two strategies.

A vision that needs a plan. France has a rare opportunity to extend its nuclear umbrella and assert its leadership on the continent by supplanting the US monopoly on nuclear deterrence in Europe and becoming a champion of European strategic autonomy. But as usual, the devil is in the details: To achieve this, Macron needs to clarify his plan to extend France’s nuclear capabilities to the rest of Europe. He also needs to convince the bloc to take its defense capabilities a quantum leap forward. The European Union held its first-ever military exercises only in 2023. Becoming a nuclear power would be a considerable step forward. But even with a clear plan, Macron is sure to be faced with EU member states opposed to nuclear weapons and with reluctant populations who doubt the credibility of France lending its nuclear arsenal for their defense.

Since de Gaulle, France has been building its nuclear capabilities as a credible independent source of deterrence. Were the European Union to seriously consider providing its own nuclear deterrence, it should naturally benefit from the expertise of one of its member states. French nuclear reassurance for the rest of the Union could be a major step that brings the bloc closer to its goal of becoming a geopolitical union and a stronger security actor. But for such a vision for European security to become a realistic plan, President Macron must first tell its European partners to what extent he is willing to share France’s nuclear deterrent.