French President Emmanuel Macron has set out a new "forward deterrence" doctrine, pledging to expand the country's nuclear arsenal while, for the first time, offering to temporarily station parts of its deterrent on allied European soil.

In a speech delivered at a submarine base in northwestern France on Monday, Macron unveiled a new, intensified, formal nuclear security partnership with eight European allies, which would be separate from but complementary to the NATO alliance.

Planned before the recent outbreak of conflict in the Middle East, the address sought to reassure Europe amid friction with United States President Donald Trump and mounting anxiety over the Russia-Ukraine conflict.

Macron signaled that Paris may deploy nuclear-capable Rafale jets in allied states such as Germany and Poland. The framework would also invite partners to join drills and commit conventional forces to support operations, reported the Financial Times newspaper.

"To be free, one needs to be feared," Macron said, adding that the new stance could "provide for the temporary deployment of elements of our strategic air forces to allied countries", while stressing there would be no transfer of decision authority to any other state regarding nuclear use.

Macron said negotiations had already begun with the United Kingdom, Germany, Poland, the Netherlands, Belgium, Greece, Sweden and Denmark.

Since the UK's exit from the European Union in 2020, France has been the bloc's lone nuclear-armed state. France maintains the world's fourth-largest nuclear stockpile, estimated at roughly 290 warheads.

Macron said France will expand its stockpile of nuclear warheads but gave no target number. This would be its first increase in the arsenal since at least 1992, reported The Associated Press.

"If we had to use our arsenal, no state, however powerful, could shield itself from it, and no state, however vast, would recover from it," Macron said.

Macron cast the shift as a response to an unstable strategic climate. "The next 50 years will be an era of nuclear weapons," he said.

European leaders are increasingly questioning US commitments to safeguard Europe under the so-called nuclear umbrella, a policy long meant to ensure that allies, especially NATO members, are protected by US nuclear forces in the face of threats, said the AP.

Macron said recent shifts in US defense strategy signal a reordering of US priorities and press Europe to assume greater responsibility for its own security. He added that Europeans should take their destiny more firmly into their hands.