A tumultuous week began with a phone call between Trump and the Turkish president

When he spoke to President Trump on the telephone a week ago Friday, Turkish President Recep Tayyip Erdogan’s agenda had not changed from when they met two weeks earlier at the Group of 20 summit in Argentina.

He repeated his inability to understand why the United States was still arming and supporting Syrian Kurdish fighters to conduct a ground war against the Islamic State. To Turkey, which shared a 500-mile long border with Syria, they were a national security threat, allied with Turkish Kurds that even the United States considered terrorists.

The Islamic State, according to Trump himself, had been defeated, Erdogan said. Turkey’s military was strong and could take on any remaining militant pockets. Why did some 2,000 U.S. troops still need to be there?

“You know what? It’s yours,” Trump said of Syria. “I’m leaving.”