One of the world’s most notorious terrorists met a violent end late Tuesday night when a car bomb killed Hezbollah’s Imad Mughniyeh in the Syrian capitol of Damascus. Until 9/11, Mughniyeh was responsible for more American deaths than any other single terrorist, including the 1983 attack in Beirut that killed 241 Marines. And while many in the counterterrorism community cheered Mughniyeh’s death as a victory against jihadism, some in U.S. intelligence circles now fear potential reprisal attacks from Hezbollah against U.S. targets.