When the US briefly halted sharing battlefield intelligence with Ukraine in March 2025, the results were immediate. Kiev’s forces suffered decisive setbacks on the battlefield as their European allies watched in horror.
The disruption lasted just a few days, but it sent shockwaves across Europe as a new reality set in: Washington was no longer a reliable military partner, and the continent needed a plan B.
Europe has struggled to keep an increasingly hostile US within NATO as countries race to rearm. And now, for the first time since the end of the Cold War, European capitals are discussing how to develop their own nuclear deterrent, according to people familiar with the matter, citing conversations between militaries and governments.
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German Chancellor Friedrich Merz confirmed that the issue is “alive” in a speech on Friday at the Munich Security Conference. “I have started confidential talks with the French president about the European nuclear deterrent,” he said. “We will not allow zones with different levels of security to emerge in Europe.”
Europe depends on the US for what is called a “nuclear umbrella”, made up of American weapons based on the continent and the NATO mutual defense pact. If the United States can no longer be trusted, Europe will face the grim prospect of being left alone at home with a neighbor, Russia, which has the world’s largest nuclear arsenal.
At the moment, only the United Kingdom and France have atomic weapons. French President Emmanuel Macron is expected to offer nuclear deterrence to the rest of Europe in a speech later this month, according to people familiar with the matter. He had already mentioned the possibility of extending the French umbrella to the rest of Europe last year, following the events in Ukraine.
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With enough money, other European countries could theoretically obtain nuclear missiles. But this would require painful choices: high costs and violations of international treaties if they want to develop their own arsenal, or the acceptance that committing to defend an ally comes with the likely tradeoff of being attacked.
“Imagine that Russia invades Estonia,” said Pavel Povdig, a senior researcher at the United Nations Institute for Disarmament Research. “So France makes that calculation — it has the capacity to do a lot of damage to Russia, but Russia would certainly do a lot of damage to France in response. Is that something Paris would be willing to contemplate?”
Europe treads delicate ground. As officials grapple with the issue, they have been careful about the signals sent to Russia, keeping talks in bilateral or trilateral formats between countries that have a strong relationship of trust, said a person familiar with the negotiations. She requested anonymity due to the sensitivity of the matter.
The countries involved in the discussions often host U.S. military assets, are close to Russia and feel directly threatened by Vladimir Putin, this person said. The talks take place at a deep military level, and not even ministers may be aware, he added.
Nuclear deterrence should be one of the hot topics in Munich. Macron’s speech on the matter will come later, in France, after consultations with his advisers, according to people familiar with the schedule.
Replacing the US “umbrella” with new European weapons is financially unfeasible for most countries, among other problems, experts said. The continent is already stretching its budgets to the maximum to expand conventional military power. In 2025, the European Union and the United Kingdom together spent more than $530 billion on defense, more than half of Poland’s entire gross domestic product.
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For now, the best move for Europe would be to develop an advanced arsenal of non-nuclear weapons capable of threatening high-value targets inside Russia and containing an invasion, according to Darya Dolzikova, a senior research fellow at the Royal United Services Institute.
“I don’t see a pan-European nuclear deterrent,” said Dolzikova, author of a recent report on nuclear deterrence in Europe. “I don’t think that’s viable. What I think there is room to do is ask: ‘How do France and the UK think about their own domestic instruments of deterrence, and how does that affect European security?'”
France and the United Kingdom have around 400 warheads deployed between them. That compares with 1,670 in the United States, a number that could grow after the expiration this month of the New START treaty between the U.S. and Russia, which limited nuclear weapons.
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Despite their smaller arsenal, French and British warheads have enough explosive power to destroy hundreds of cities, according to Dolzikova. Russia, in contrast, is more agile: its vast arsenal includes smaller weapons, giving it more targeting and response options in any escalation.
The United Kingdom and France spend around $12 billion a year together to maintain their weapons. That’s more than half of the entire defense budget of Sweden, NATO’s newest member.
Convincing voters to accept that expensive nuclear weapons protect other countries — even if the costs don’t rise — can be a difficult task. Both Paris and London are already facing complaints from taxpayers as governments make tough budget choices.
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The two countries have held talks about how to better coordinate their nuclear forces. Last year, they signed the Northwood Declaration, which stated: “Our nuclear forces are independent but can be coordinated and contribute significantly to the overall security of the Alliance and to peace and stability in the Euro-Atlantic area.”
France could deploy fighter jets capable of carrying nuclear weapons in other European countries such as Poland, according to a report by Paris-based think tank IFRI. Simpler options include increasing the participation of NATO countries in French nuclear exercises or closer ties between France and the NATO Nuclear Planning Group.
Individual countries could invest in “turnkey” capabilities, meaning having all the elements ready to build a nuclear weapon if necessary. But even that requires nuclear plants, complex and expensive enrichment facilities and the political willingness to violate nonproliferation agreements, according to a person familiar with European nuclear discussions.
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“It is a very complicated issue because the French nuclear deterrent is not a de facto nuclear umbrella, like the one NATO offers us,” Belgian Prime Minister Bart De Wever told Bloomberg. “If you talk about nuclear weapons, then you are talking about spending a lot of money.”
From the perspective of their partners, it is also not guaranteed that the United Kingdom and France will always have governments committed to the idea of protecting the rest of Europe, said IFRI researcher Heloise Fayet. France is due to hold presidential elections next year, and Marine Le Pen and her right-hand man Jordan Bardella have openly protested any idea of shared nuclear deterrence.
“Our allies may come to the conclusion that they cannot trust us,” Fayet said. “Credibility requires acting quickly and creating habits.”
NATO, in turn, has been reinforcing its message of unity. Secretary-General Mark Rutte has repeated that Americans remain fully committed to the transatlantic alliance. A Defense Department official in Washington said the US continues to extend nuclear deterrence to its allies.
In fact, when the US talks about Europe taking care of its own security, it is about conventional defense. President Donald Trump has not mentioned the nuclear umbrella, and the United States has not raised the topic in private conversations, according to people familiar with the matter. The White House did not respond to a request for comment.
In turn, the UK’s arsenal is deeply linked to the US. Although the United Kingdom has operational independence of its nuclear deterrent, and the submarines are British-made, its missiles are produced by the American defense company Lockheed Martin.
Unlike France, the United Kingdom attributes its nuclear deterrence to NATO defense since 1962, being the only European nation to do so. This means it does not need to negotiate and sign bilateral umbrella agreements with other members.
But the challenges and costs of developing nuclear weapons to rival those of the US are likely to keep European ambitions more modest. “If you want a multi-layered nuclear umbrella, then you are quickly moving towards becoming a world power,” said Belgian De Wever. “I’m not sure Europe needs to go that far.”
© 2026 Bloomberg L.P.
