Car attacks have become a key tactic in ISIS’ worldwide killing campaign because they require few resources, almost no training, and minimal planning. They also weaponize everyday vehicles and turn public spaces into killing zones. As a result, they are nearly impossible to defend against. “The insight is anyone can pull this off, even when there are defensive countermeasures put in place,” said Clint Watts, a former FBI counterterrorism special agent and U.S. Army officer, in a phone interview. Vehicular terrorism also dovetails with ISIS’ recent strategy of inspiring lone assailants rather than orchestrating grandiose attacks from afar. Such attacks are expected to continue as ISIS loses ground in Iraq and Syria, where it’s based.