A Franco-British Nuclear Umbrella as Clouds Gather

Mint

15-07-2025

(Bloomberg Opinion) -- Lost in the noise of President Emmanuel Macron's state visit to London, where British frustrations over migrants crossing the Channel drowned out geopolitical issues, was a remarkable turning point for the atomic age: an announcement to coordinate Europe's only two nuclear arsenals and their response to any 'extreme' threat to European security.
It's a forceful attempt to address the twin defense pressures facing the continent, namely a US administration whose reliability as an ally is in doubt and a Russia less deterred by Western pressure. Only four years ago, Macron was humiliated by the Anglosphere when the Aukus deal torpedoed a key French submarine agreement with Australia. He's proving somewhat more successful at binding the Brits closer to European goals with Keir Starmer these days, when the US-UK relationship no longer feels quite so special and when they're all facing a tariff hit. Macron's upgraded defense agreement with Starmer comes after a recent French treaty with Poland and armaments cooperation with Sweden.
The word 'coordination' has been carefully chosen. It does not mean 'shared': Charles De Gaulle, who equated France's nuclear deterrent with autonomy outside the Atlantic alliance — and the US security umbrella — would likely be spinning in his grave. Coordination could offer benefits even without being a convincing alternative to American hard power, according to Andrea Gilli, a lecturer in strategic studies at the University of St Andrews. Nuclear submarines that are reserved for training or maintenance could be offset by the partner country's. Knowledge-sharing might involve intelligence about enemy forces, capabilities and plans.
This is all helpful in preventing the complex global 'balance of terror' from being too lopsided, even if the reality is that London and Paris's combined 500-plus warheads only account for a fraction of those owned by Russia and the US. And with both France and the UK also pledging to collaborate on conventional weapons, from missile production to artificial intelligence, it's a signal that they intend to be heard by Donald Trump, who is pushing NATO allies to step up on security, and Vladimir Putin, who has been waiting for European resolve to crumble for years. Macron's voice on the international stage may be fading in the twilight of his presidency, but even Germany is sounding a little more Gaullist.
This still feels, however, like a very tentative first step toward bolstering continental security that will require a lot of follow-through. There are still clear strategic differences between France and the UK, with the latter's nuclear deterrence highly reliant on the US and limited to one type of launch platform via submarine (whose test launches have a tendency to fail.) Even in the event this partnership becomes a solid basis for a new nuclear umbrella, it will require a lot more investment, with think tank Bruegel estimating modernization costs alone for both countries' deterrence at €100 billion ($117 billion). De Gaulle once asked John Kennedy if the US would trade New York for Paris in the event of a nuclear strike; tomorrow, allies may wonder what London and Paris are willing and able to sacrifice together in a world where the US can't be counted on.
With rising defense powers Poland and Germany increasingly thinking about their own 'nuclear option,' Europe has to urgently decide on a strategic path. One is finding more ways to share the burden of a truly continental nuclear umbrella, with 'coordination' a starting point. Another is allowing neighbors to get closer to acquiring nukes themselves. The first option would be preferable to letting nuclear weapons proliferate but brings its own challenges to sovereignty and credibility.
If Macron, Starmer and others don't make quicker headway on these questions, Putin admirers like Marine Le Pen, Nigel Farage and Matteo Salvini — who once said he wouldn't want to put his child's future in Macron's hands — will.
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Lionel Laurent is a Bloomberg Opinion columnist writing about the future of money and the future of Europe. Previously, he was a reporter for Reuters and Forbes.
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