In Tense Exchange, Trump and Macron Put Forth Dueling Visions for NATO

President Trump said a warning from President Emmanuel Macron of France that Europe could no longer assume American support was “a very dangerous statement.” Mr. Macron said he stood by it.

A once-cordial relationship between President Trump and President Emmanuel Macron of France devolved in a dramatic fashion on Tuesday, as the two leaders publicly sparred over their approach to containing the threat of terrorism and a shared vision for the future of NATO, a 70-year-old alliance facing existential threats on multiple fronts.

In a lengthy appearance before reporters, the president met a cool reception from Mr. Macron, who earlier in the day Mr. Trump derided as “very insulting” for his recent remarks on the “brain death” of the alliance. When asked to address his earlier comments on the French leader, Mr. Trump, a leader averse to face-to-face confrontation, initially demurred, but Mr. Macron was direct.

“My statement created some reactions,” Mr. Macron said. “I do stand by it.”

What followed was an extended, terse back-and-forth over trade, immigration, and Mr. Trump’s relationship with President Recep Tayyip Erdogan of Turkey.

Mr. Trump’s interactions with the Turkish president are also sure to be closely watched. Mr. Erdogan, who has already upset NATO allies by purchasing a sophisticated Russian antiaircraft missile system, the S-400, is now threatening to oppose NATO’s plans to update the defense of Poland and the Baltic countries if the alliance does not join him in labeling some Kurdish groups as terrorists.