IT WAS LONG PAST MIDNIGHT IN GENEVA last November when the rumors began to fly. Iran and the world powers had just reached a deal on its nuclear program. An international crisis that had been building toward what seemed like war for more than a decade was now on the path to resolution. The deal, a haggard John Kerry confirmed, was real. It wasn’t comprehensive—Iran would still be heavily sanctioned and heavily centrifuged—but it was unprecedented. All prior efforts had fallen apart.