French President Emmanuel Macron said Monday that France will increase its stockpile of nuclear warheads – currently below 300 – marking the country’s first expansion of its nuclear arsenal since at least 1992, though he did not specify the size of the buildup.

"I have decided to increase the numbers of warheads of our arsenal,” Macron said at a military base at L’Ile Longue in northwestern France that hosts the country’s ballistic missile submarines.

Macron’s speech was aimed at spelling out how French nuclear weapons fit into Europe’s security amid concerns raised on the continent by recurring tensions with U.S. President Donald Trump.

European leaders have voiced growing doubts about U.S. commitments to help defend Europe under the so-called nuclear umbrella, a policy long intended to ensure that allies – particularly NATO members – would be protected by American nuclear forces in the event of a threat.

France is the only nuclear power in the European Union.

Some European nations have already taken up an offer Macron made last year to discuss France’s nuclear deterrence and even associate European partners in nuclear exercises.

Earlier this month, German Chancellor Friedrich Merz said he’d had "initial talks” with Macron on the issue and had publicly theorized about German Air Force planes possibly being used to carry French nuclear bombs.

France and Britain also adopted a joint declaration in July that allows both nations' nuclear forces, while independent, to be "coordinated.” The U.K., no longer an EU member but a NATO ally, is the only other European country with a nuclear deterrent.

Macron has consistently insisted that any decision to use France’s nuclear weapons would remain only in the hands of the French president.