President Donald Trump on Tuesday, Dec. 3, blasted President Emmanuel Macron over the French leader’s criticism of NATO, and condemned the other members of the military alliance for being too slow to beef up their defense budgets, according to The Associated Press.

As leaders of the 29-member alliance gathered in London to mark NATO’s 70th birthday, Trump told reporters Macron’s comments were “very, very nasty” when he lamented the “brain death” of the organization due in large part to a lack of U.S. leadership,The Associated Press reported.

“NATO serves a great purpose,” Trump told reporters during a meeting with NATO Secretary General Jens Stoltenberg in London.

“It’s a tough statement. When you make a statement like that, that is a very, very nasty statement essentially to 28 countries,” President Trump said.

“I think that’s insulting to a lot of different forces,” President Trump said. “You just can’t go around making statements like that about NATO. It’s very disrespectful.”

President Trump also said that Macron’s statement was “very dangerous.”

“Nobody needs NATO more than France,” he said.

In an interview with The Economist, Macron questioned the commitment from the United States in the alliance when the Trump administration pulled troops out of northern Syria last month, a move that Turkey saw as a green light for an invasion. 

“What we are currently experiencing is the brain death of NATO,” Macron said.

“I don’t know” Macron said, referring to the collective defense clause. “But what will Article Five mean tomorrow?”

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

During the summit President Trump also raised the budget commitment from NATO members, saying that “a lot of countries haven’t paid.” 

The president has often criticized NATO, arguing that the United States contributes an unfair amount to fund the alliance and protects other member nations that pay less.

Earlier on Monday, the president mentioned an increase in defense spending from other nations during his administration.

“In the 3 decades before my election, NATO spending declined by two-thirds, and only 3 other NATO members were meeting their financial obligations. Since I took office, the number of NATO allies fulfilling their obligations more than DOUBLED, and NATO spending increased by $130B!” he tweeted.

President Trump is expected to meet Macron on Tuesday on the sidelines of the summit.

In a different development, on Monday, Dec. 2, Trump administration just announced to impose huge tariffs on billions of French goods in response to France’s digital tax on large tech companies.  

Includes reporting from The Associated Press