Qassem Suleimani was Iran’s most powerful military and intelligence leader, and his killing, in a U.S. air strike in Baghdad on Thursday night, will likely be taken as an act of war by Tehran. Dexter Filkins, who wrote the definitive profile of Suleimani, in 2013, spoke with David Remnick about the commander’s central role within the Iranian regime. Reprisals against the U.S., he says, might be carried out anywhere in the world, either by Iran’s Quds Force or by affiliates such as Hezbollah. The Trump Administration experiences tension between a desire for regime change and the President’s desire to avoid foreign wars; Filkins notes that embattled Presidents, like Bill Clinton during his impeachment, often have itchy trigger fingers.