Norway will begin talks on joining a France-led nuclear deterrence program, the countries' leaders announced, a move that, if concluded, would be a notable shift for a traditionally Atlanticist nation long aligned with the United States on security.

France's President Emmanuel Macron and Norway's Prime Minister Jonas Gahr Store signed a mutual defense agreement during a meeting in Paris on Wednesday.

The deal would see Norway join what France describes as "forward nuclear deterrence", which is a framework that would involve European partners more closely in French strategic nuclear planning, Reuters reported.

The announcement comes amid widening European doubts about long-term US guarantees and efforts to build a more autonomous European defense posture, as even staunch US-oriented allies recalibrate.

"This agreement establishes a principle of mutual assistance between our two countries," Macron said.

Oslo's primary security guarantee would remain the NATO military alliance and the United States, said Store, but noted that France's nuclear capabilities reinforce the broader deterrent.

"We are contending with the most serious security situation since the Second World War," Store said.

"The agreement reinforces our cooperation through concrete structures, plans, exercises and prepositioning of equipment, and will enable us to mount a swift and coordinated response when it is really needed."

The Norwegian leader added that the agreement also provides a framework for closer cooperation on hybrid warfare, maritime security, space cooperation, cybersecurity, support for Ukraine and defense industrial cooperation.

In a social media post after the meeting, Macron added: "In the face of threats to our continent and beyond, Europeans need to be stronger and more sovereign. Our strengthened partnership serves to demonstrate this."

Norway would become the ninth country to come under the French nuclear umbrella, highlighting Europe's growing doubts about relying on US security guarantees.

Earlier this year, France offered to extend its nuclear umbrella to additional European states, which effectively means an attack on Norway could prompt a French nuclear response.

Under the initiative, participants could temporarily host French "strategic air forces", enabling them to disperse across Europe and "complicate adversaries' calculations", Macron said at the time.

As the European Union's sole nuclear-armed power, France has deepened strategic cooperation with several European allies — including Germany, the Netherlands, Sweden, Denmark, Belgium, and Greece — that have signed on to its nuclear deterrence initiative.

Once the agreement is concluded, Norway would follow Poland and Lithuania in coming under France's nuclear protection.

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