Three acts of ideologically inspired violence in the last week have laid bare the heightened terrorism threat unfolding against the backdrop of a U.S. war with Iran and a counterterrorism system strained by the widespread departures of experienced national security professionals at the FBI and Justice Department. The firings and resignations, coupled with the diversion of resources over the last year to meet other Trump administration priorities, have heightened concerns about the capability to head off a potential surge in threats. Iran has vowed revenge for the killing of Supreme Leader Ali Ayatollah Khamenei, and though the fighting has been confined to the Middle East, the Islamic Republic has long been determined to carry out violence on American soil.