Peter Bergen , David Sterman : First American known killed while fighting for ISIS . Writers : Other Americans drawn to Americans , ISIS in Syria ; 100 have fought or tried to . No ISIS involved with ISIS or ISIS charged with plotting attack inside Syria , they say . Abdella Tounisi , an 18-year-old American citizen from Aurora , Illinois , was arrested and charged with attempting to provide material support to Nusra . Writers : Tracking the foreign fighters is a key priority for counterterrorism efforts .
Peter Bergen , David Sterman : First American known killed while fighting for ISIS . Writers : Other Americans drawn to Americans , ISIS in Syria ; 100 have fought or tried to . No ISIS involved with ISIS or ISIS charged with plotting attack inside Syria , they say . Writers : Tracking the foreign fighters is a key priority for counterterrorism efforts .