French President Emmanuel Macron has warned Europe is facing the "brain death of NATO," caused by American indifference to the transatlantic alliance.

Macron told the Economist in an article published Thursday that Europe can no longer rely on the United States to defend NATO allies.

His blunt comments come after the Trump Administration pulled US forces out of northern Syria last month, in a move that dismayed European NATO members.

The abrupt withdrawal — seemingly without warning to Paris — left US allies, the Syrian Kurds, open to a Turkish offensive in the region.

Macron has been a vocal supporter of the Kurds, and the sudden US policy shift complicated relations with fellow NATO member Turkey.

NATO is a collective defence alliance that emerged during the Cold War, and under its founding charter, an attack on one member elicits a response from the alliance.

Macron told the Economist that Nato “only works if the guarantor of last resort functions as such. I’d argue that we should reassess the reality of what NATO is in the light of the commitment of the United States.”

He added that the US “shows signs of turning its back on us.”

The French President, who has been a vociferous supporter of the European Union, said Trump “doesn’t share our idea of the European project.”

This threat coincides with the rise of China, the authoritarian turn of regimes in Russia and Turkey, and Europe being weakened from within by Brexit and political instability, he added.