Since September 11, 2001, al‑Qaeda has pulled off exactly one fatal attack inside the United States. “The al‑Qaeda concept has taken root,” he said, and has given the group’s leadership—sometimes called “al‑Qaeda core”—the luxury of deciding when to begin killing Americans again. (As an extremist-Sunni group, al‑Qaeda is not a natural ally of extremist-Shiite Iran.) The various affiliates call themselves al-Qaeda, but they appear to take no meaningful guidance from anyone in al‑Qaeda core. Daniel Byman, a veteran al-Qaeda watcher at Georgetown University, reminded me that al-Qaeda has not even officially announced that Saif al-Adel is in charge.