LONDON — U.S. President Donald Trump landed Tuesday in London with a splash, decrying French President Emmanuel Macron’s recent description of NATO as brain dead, calling it a “nasty” assessment and unfair to the alliance.

Trump’s remarks on the eve of a meeting of government leaders here on Wednesday come as NATO members are already on edge about myriad internal differences. Clashing views have become so pronounced in the last few weeks that some observers fear the worst for what has been billed as NATO’s 70th birthday bash.

“You just can’t go around making statements like that about NATO,” Trump said of Macron in a joint news conference with Secretary General Jens Stoltenberg. “It’s very disrespectful.”

The U.S. president’s words are remarkable not for their tone — he also delivered an en passant bashing of French politics and economy — but for the substance of the argument. Trump, who has shown a deep disdain for the mere principle of multilaterlism, appears to be shielding NATO from Macron’s critique, which in turn was partly aimed at himself.

Talk about the three-dimensional chess of geopolitics. Or something like that.

Stoltenberg, for his part, sought to downplay any cracks within the alliance, arguing in typical fashion that healthy squabbling should be expected in any group of countries working together.

“If you look at the substance, you can see that the alliance is delivering,” he said at the NATO Engages think tank event in central London. He named ongoing operations to secure the eastern flank against Russia, the training of security forces in Iraq and an uptick in defense spending by all allies in recent years as examples of an alliance that continues to be operationally relevant.

Stoltenberg was noncommittal, however, on the latest curveball thrown by member country Turkey. The Turks want their perception of a terrorist threat posed by YPG Kurdish units to their border with Syria recognized by all of NATO as a quid pro quo for backing the alliance’s bolstering of the Baltics. Such a deal could cause a significant rift.

Trump is an admirer of Turkish President Recep Tayyip Erdoğan, and will likely get more deeply involved in the issue during meetings here.

“Turkey does not question the alliance, but rather Turkey expects an understanding of the threat of terrorism to one of its allies,” Gülnur Aybet, Erdogan’s senior adviser on foreign policy, told the NATO Engages audience.

“We don’t question the credibility of Article 5. On the contrary, we expect it to be fulfilled,” she added, referring to the alliance’s creed that an attack on one member will prompt a response by all.