Meeting in London this week, leaders of the North Atlantic Treaty Organization have two other presidents to worry about: France’s Emmanuel Macron, who recently has openly questioned the collective defense clause at NATO’s heart, and Turkey’s Recep Tayyip Erdogan, who has troubled alliance members with his decisions to send troops into Syria and buy a Russian anti-missile system.

To make matters worse, Macron and Erdogan are now trading insults in public.

In fact, so much has changed since then-Prime Minister Theresa May offered to host the two-day commemoration of NATO’s 70th anniversary that her successor, Boris Johnson could be forgiven for wishing she hadn’t.

“I will tell you again at NATO, first check your own brain death,” Erdogan said, addressing Macron in a speech from Istanbul on Friday. He was referring to an interview the French leader gave last month in which he not only criticized Turkey, but described the alliance as brain dead.