France, UK may extend nuclear protection to EU allies

France and the UK say they’ll respond to any major threat to Europe together, in an effort to reassure EU allies nervous about Washington’s commitment to their security.

French President Emmanuel Macron with UK Prime Minister Keir Starmer. Picture: Getty Images.

France and the UK, Western Europe’s two nuclear powers, said on Wednesday that they will now co-ordinate the use of their nuclear weapons and respond to any major threat to Europe together, a step seen as an effort to reassure European allies who are nervous about Washington’s commitment to the continent’s security.

The move, announced during a state visit to the UK by French President Emmanuel Macron, appears to offer both countries’ nuclear weapons as a deterrent for all of Europe while establishing greater independence from any safety net provided by the US’s much larger arsenal.

While both France and the UK are part of the North Atlantic Treaty Organisation, where an attack on one member triggers a collective defence, their nuclear weapons were considered independent of this obligation.

Both countries are increasingly referring publicly to their nuclear arsenals amid concerns over Russian aggression and as President Trump has occasionally questioned the US’s post-World War II commitment to the defence of Western Europe.

“It’s decoupling from the US without saying it,” said Phillips O’Brien, a professor of strategic studies at the University of St. Andrews, in Scotland.

France's President Emmanuel Macron was on a state visit to the UK. Picture: AFP.

France and Britain have a combined estimated 515 nuclear warheads, a fraction of the over 5,000 held each by the US and Russia. Still, the devastating power of even one nuclear warhead means that Britain and France’s stockpile remains a credible deterrent.

Several European nations, including Germany, have previously called for the UK and France’s deterrent to be extended to cover more of the region. Those calls have been particularly loud since Russia’s full scale invasion of Ukraine in 2022 and increased nuclear sabre-rattling from Moscow.

The UK said on Wednesday that a signed declaration with France will state for the first time that the respective deterrents of both countries, though independent, can now be co-ordinated.

“Any adversary threatening the vital interests of Britain or France could be confronted by the strength of the nuclear forces of both nations,” the Ministry of Defence said in a statement.

The agreement goes further in suggesting their so-called nuclear umbrella will now be extended across the region.

“There is no extreme threat to Europe that would not prompt a response by both nations,” it said.

For the first time, the two countries will now establish a military and political group that can co-ordinate nuclear response. While a sudden nuclear attack would allow little time for co-ordination, this could happen amid any build-up of nuclear tension.

Mr Macron has for years pushed European leaders to develop strategic autonomy and reduce their reliance on the US. Mr Macron has invited European allies to participate in French nuclear-force exercises and to discuss how French deterrence capabilities could bolster European security. Mr Macron has repeatedly said that the decision to strike would always be in the hands of the French president.

The move marks more of a shift for the UK, whose defence establishment has a particularly close relationship with the US and where politicians are wary of European military co-ordination.

What has changed is Russia’s invasion of Ukraine and Trump, who has questioned whether the US would defend allies who don’t pay their way, making some European countries feel exposed.

At a recent NATO summit, European nations pledged to raise defence spending to 5 per cent of GDP within 10 years, and Trump declared the alliance was no longer “a rip-off.” Still, European allies are increasingly aware that they might not be able to count on the US, especially if the US shifts more of its focus to Asia and the threat from a more aggressive China.

The UK also said last year that it is looking into producing more of the material that goes into its nuclear deterrent, which is currently partly dependent on the US. That came the day after Trump was elected president. Trump has long signalled a general disengagement from Europe’s defence.

Britain helped the US build the first nuclear weapon, and it was the third nation to develop warheads, but its deterrent is highly dependent on America. The submarine-launched missiles that carry British nuclear warheads, for instance, are US made. France’s nuclear deterrent is independent of the US.

“This marks a major evolution in the (military) relationship between France and the UK, and for European defence,” said Jean-Louis Lozier, a former French Navy officer who commanded ballistic missile submarines and headed the army’s nuclear forces division.

The move will increase Europe’s strategic autonomy, he said. Still, France and Britain, as Europe’s currently most significant military powers, have frequently made announcements of increased co-operation which rarely appear to lead to much actual collaboration. The two countries have also agreed to nuclear collaboration before, in researching new warheads.

Nick Cunningham, a defence analyst at Agency Partners LLP, said the new agreement could be very significant.

“But is it just warm words, or will it have a practical expression?” he said.

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