Two - thirds of Americans say ' ` ` major threat '' to U.S. Government officials have estimated numbers of Americans fighting for ISIL , says Peter Bergen . Claims that over 100 U.S. citizens fighting with ISIS are probably overestimate . This example suggests those fighting in Syria wo n't be U.S. citizens , Bergen says .
Two-thirds of Americans say ISIS `` major threat '' to U.S. U.S. officials have inflated numbers of Americans fighting for ISIS , says Peter Bergen . Claims that over 100 U.S. citizens fighting with ISIS are probably overestimate . Somalia example suggests those fighting in Syria wo n't pose U.S. threat , Bergen says .