Sebastien Lecornu said NATO allies needed to think long-term and beef up their defence industries as Washington demands that Europe take security into its own hands.

"It's a crucial moment of truth," Lecornu told reporters ahead of a NATO meeting in Brussels.

"People call it the most important, the strongest military alliance in history. That's historically true -- but the question is, will it still be true 10 or 15 years from now."

US President Donald Trump on Wednesday blindsided Ukraine and Washington's European allies by agreeing to launch peace talks in his first publicly announced phone call with Putin since returning to power.

On Thursday, ahead of the Brussels NATO talks, US Secretary of Defense Pete Hegseth described the Ukraine conflict as "a factory reset for NATO, a realization that this alliance needs to be robust and strong and real".

He echoed Trump's demands for allies to more than double their defence spending target to five percent of GDP, although he seemed to allow for some leeway suggesting growth could be incremental.

"Two percent of GDP is not enough. Three and four and ultimately, as President Trump has said, five percent of defense spending is critical," Hegseth said.

"There is a Russian war machine that has sought to take more and more land in Ukraine, and standing up against that is an important European responsibility."

The United States has underpinned European security through NATO over the past seven decades.

US allies have already stepped up their spending in the face of Russia's invasion of Ukraine and are pledging to do more to back Kyiv.

Lecornu said France and others were committed to do more -- but warned money had to be spent wisely, arguing that simply filling "hangars" with US gear, "without seeking real military efficiency" would be a historic "failure" for Europe.

Lecornu is a staunch loyalist of French President Emmanuel Macron, a fierce proponent of a more militarily independent Europe who once described NATO as brain dead during Trump's first term and is pushing for EU countries to buy European when it comes to defence.

Conveying European fears that Trump could force Ukraine into a bad peace deal, he warned that this could embolden Putin and other western rivals, including Iran, North Korea and China.

"Either we are within the parameters of a discussion that will genuinely bring peace through strength, or, on the contrary, it will be peace through weakness", he said adding the latter could lead to "dramatic security situations" and a "widening of the conflict".