Turkish President Recep Tayyip Erdogan lashed out on Friday at Emmanuel Macron over his criticism of Turkey's military intervention in Syria, saying the French president was suffering "brain death", a phrase Macron recently used to describe NATO.
Erdogan used a televised speech to launch a stunning attack on Macron, just days before the two men join other NATO leaders in England for events to mark the alliance's 70th birthday.
"I am talking to France's President Emmanuel Macron, and I will also say this at NATO. First of all, have your own brain death checked. These statements are suitable only to people like you who are in a state of brain death," Erdogan said.
He was referencing Macron's much-publicised recent claim that NATO was suffering "brain death" owing to the lack of strategic cooperation among members.
"You know how to show off but you cannot even properly pay for NATO. You are a novice," Erdogan said.
The French government said it would summon the Turkish ambassador in Paris for talks over the broadside, the second time it has called in the envoy in as many months.
"This is not a statement, these are insults," a official in the presidency said, adding: "The ambassador will be summoned to the ministry to explain things."
Erdogan appeared particularly irked by Macron's criticisms of Turkey's cross-border offensive in October against a Western-backed Kurdish militia that had been leading the fight on the ground against Daesh in Syria.
The Turkish offensive killed dozens of civilians, mainly on the Kurdish side, and prompted hundreds of thousands to flee their homes.
During a press conference alongside NATO chief Jens Stoltenberg in Paris on Thursday, Macron said he understood the security concerns of "our Turkish ally, which has suffered several attacks on its soil."
But it was unacceptable for Turkey to present its allies "with the fait accompli of a military operation that endangers the actions of the anti-Daesh coalition of which NATO is a member," he added.
Seizing on the remarks, Turkey's 64-year-old president accused 41-year-old Macron of being "very inexperienced."
"He doesn't know what fighting against terror is. That is why yellow vests invaded France," he added, in a swipe over the protests that badly rattled Macron's government last year.
Erdogan said Ankara had a right to intervene in Syria given the two countries' shared border.
"What is your business in Syria?" he said, addressing Macron. "Jump up and down as much as you like ... you will respect Turkey's right to fighting against terrorism sooner or later. There is no other way."
The war of words adds to the tensions among NATO members that threaten to overshadow next week's summit.
National leaders are bracing for a scrap over spending and how to deal with Russia, in a huge test of NATO's unity.
Macron set the ball rolling for a fractious gathering by describing the club in a November 7 interview with The Economist magazine as suffering from "brain death".
In support of his assessment, he cited the shock decision by US President Donald Trump to withdraw troops from northern Syria and the ensuing Turkish offensive against the Kurdish YPG militia which Ankara views as terrorists.
Friday was not the first time he came under attack from Ankara after proferring criticism of Turkey.
In October, Foreign Minister Mevlut Cavusoglu likened him to a "crowing cockerel" after Macron criticised Ankara's record on human rights in a speech at the Council of Europe.
Didier Billion, a researcher at the French Institute for International and Strategic Affairs, described the deterioration in relations between France and Turkey as "nearly as serious as during the time of (ex-president Nicolas) Sarkozy."
Sarkozy drew Turkey's ire by opposing Turkey's Turkey EU membership ambitions.