ISTANBUL/PARIS (Reuters) - Turkish President Tayyip Erdogan said on Friday that Emmanuel Macron’s warning that NATO was dying reflects a “sick and shallow” understanding, telling the French president “you should check whether you are brain dead”.

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The comments drew a swift rebuke from the French foreign ministry, which summoned Turkey’s ambassador to Paris to protest over what a French presidential adviser called “insults”.

Erdogan was speaking days ahead of a summit of the military alliance, which Macron has said is experiencing “brain death” because of U.S. unpredictability under President Donald Trump and strained ties with Turkey.

The Turkish and French presidents, who have traded criticism over Ankara’s cross-border offensive in northeast Syria, will be among NATO leaders meeting at a summit of the transatlantic alliance in Britain on Dec. 4.

“I’m addressing Mr Macron from Turkey and I will say it at NATO: You should check whether you are brain dead first,” Erdogan said.

Macron said in an interview three weeks ago there was a lack of strategic coordination between European allies on the one hand and the United States and Turkey, on the other. He has also decried NATO’s inability to react to what he called Turkey’s “crazy” offensive into northern Syria.

On Friday, French officials said they expected substantial clarifications from Erdogan rather than a war of words.

“Let’s be clear, these are not statements, they are insults,” a presidential adviser said. “The president says things clearly. It’s up to Turkey to provide the answers that we and many allies expect.”

Macron’s adviser said that beyond the issue of Turkey’s offensive in Syria, its refusal to back a NATO defense plan for the Baltic republics and Poland was unacceptable.

“Turkey can’t take the defense plans of Poland and the Baltic countries hostage,” the adviser said.

Turkey is refusing to back a NATO defense plan for the three Baltic states and Poland unless it secures more political support from its allies for its fight against Kurdish YPG militia in northern Syria.

Ankara views the YPG as terrorists with links to militant Kurdish separatists in southeast Turkey.

Macron’s remarks on NATO drew strong reaction from France’s neighbors who say Europe still has to rely heavily on the U.S.-led alliance for its defense. Macron said on Thursday his remarks had been a useful wake-up call and that he would not apologize for saying them.