I Went to Syria and Met the People Trump Just Gave Turkey Permission to Kill

At the headquarters of the Syrian Defense Forces in Hasaka, three white men in camouflage pull up in a pickup truck. The commander, a thirtysomething Frenchman with a closely shaved head, is driving. A somber, mustachioed Irishman is in the passenger seat. In the back, a skinny American who looks to be in his late 20s is sitting with an M16 nestled between his legs. He invites me to get in. “Where are you from?” I ask.

He asks that I call him Berxwedan, the Kurdish word for “resistance,” but...