News that Osama bin Laden had been killed lifted Americans’ spirits—celebrations broke out at ground zero, Times Square, and in front of the White House—but they should raise their guards as well: The State Department has put U.S. embassies on alert and warned Americans abroad over possible reprisals. The reins of al Qaeda now belong to Ayman al-Zawahri, previously the terrorist organization’s Egyptian-born No. 2. He is believed to be hiding on the Afghanistan-Pakistan border.
