The speech by French President Emmanuel Macron, at France's Ile Longue nuclear submarine base, comes after the launch of US and Israeli attacks against Iran in a campaign that risks destabilising the Middle East.

"What we are experiencing demonstrates that in the world to come, power and independence will be two indispensable forces for dealing with the proliferation of threats," said a member of Macron's team.

Macron is set to update France's nuclear doctrine as Russia's war against Ukraine grinds into a fifth year and NATO allies worry about Washington's wavering commitment to Europe.

"There will undoubtedly be some significant shifts and developments," a source said of the speech set to be delivered from 1415 GMT Monday.

European nations, which have relied on the US nuclear deterrent throughout the Cold War and in the decades since it ended, are increasingly debating whether to bolster their own atomic arsenals.

Paris has been in talks with countries including Germany and Poland over how France could use its atomic arsenal to help protect the continent.

Last year, Macron said he was ready to discuss possible deployment of French aircraft armed with nuclear weapons in other European countries.

Macron said in February he was considering a doctrine that could include "special cooperation, joint exercises, and shared security interests with certain key countries.

France maintains the world's fourth-largest nuclear arsenal, estimated at around 290 warheads. Britain, which is no longer a member of the EU, is the only other European nuclear power.

By contrast, the United States and Russia, the world's two main atomic powers, have thousands of nuclear warheads each.

- '27 buttons' -

Reassurances from US officials that Washington's deterrent would continue to cover Europe under the NATO alliance have done little to quell European fears of fickleness under US President Donald Trump.

"It is clear that we will need to reflect together on how French and British deterrence can fit into a more assertive European defence," Bernard Rogel, who served as top military adviser to Macron, told AFP.

But how exactly nuclear cooperation would work between the EU's 27 states is another story.

Rogel insisted that control over the launch decision will remain in French hands.

"I can't see us having 27 buttons. From a credibility standpoint, that just doesn't work," he said.

- 'Only a good thing' -

Rafael Loss, a policy fellow at the European Council on Foreign Relations, said leaders should find confidence in European support for strengthening nuclear deterrence.

He said people in Denmark, Estonia, Germany, Portugal, Spain and Switzerland now tend to support rather than oppose the idea of developing an alternative European nuclear deterrent.

"If there's going to be some kind of bigger European investments in France or UK's nuclear deterrence, that's only a good thing," Finland's defence minister Antti Hakkanen told AFP in February.

Florian Galleri, a historian specialising in nuclear doctrines, warned that Macron would have to tread carefully, pointing to his low approval ratings one year before the end of his presidency.

Macron's address could also spark a backlash ahead of the 2027 presidential election, in which Marine Le Pen's eurosceptic far-right is seen as having its best chance yet at winning the top job.

"There is a consensus on possessing nuclear weapons in France, but not on nuclear policy," Galleri said.

The far-right has already issued a warning.

"If Mr. Macron thinks he can give France's nuclear weapon to the EU, he will face impeachment proceedings for treason," Philippe Olivier, an advisor to Le Pen, said on X.