(CNN) 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.

"You have partners together in the same part of the world, and you have no coordination whatsoever of strategic decision-making between the United States and its NATO allies," said Macron.

'No coordination between members'

NATO is a collective defense 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 the alliance "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.

NATO Secretary General Jens Stoltenberg later distanced himself from Macron's comments. "Any attempt to distance Europe from North America risks weakening the alliance -- the transatlantic bond -- but also to divide Europe," he said when asked to respond. "So therefore, we have to stand together.

"I welcome European unity. I welcome efforts to strengthen European defense. But European unity cannot replace transatlantic unity."

German Chancellor Angela Merkel also disagreed with Macron. "The French President has found a rather drastic word to express his view. This is not how I see the state of cooperation within NATO. I don't think such a sweeping judgement is appropriate," she said.

A 70-year relationship

Macron's comments come at a delicate time in NATO's long history.

Next month members will meet at a summit in London to mark the alliance's 70th anniversary. And while several US presidents have bemoaned American spending on the alliance over the years -- including Barack Obama and George W. Bush -- none have been as vocal as Trump.

From as early as his 2016 election campaign, Trump branded the alliance "obsolete." He has also constantly complained about the amount NATO members spend on defense throughout his presidency.

"It's costing us too much money and frankly they have to put up more money ... we're paying disproportionately," Trump said in a CNN town hall event in March 2016.

Trump's frustration with NATO also appears to be rooted in a more fundamental hostility to the concept of collective and multilateral cooperation that has united the post-World War II American-led community of democracies.

Indeed Trump has a record of pulling out of multilateral arrangements, like the Paris climate accord and the Trans-Pacific Partnership , and he is also railing against the World Trade Organization.

Trump's and his own commitment to NATO has also been clouded by his cozy relationship with Russian President Vladimir Putin. One big fear is that Trump could hint publicly that the US will not defend alliance members who fall short of spending targets -- a step that would fracture the notion of collective defense that is central to NATO's identity, and undoubtedly delight Moscow.