American authorities over the past year or so have arrested and charged several people of supporting ISIS. Just last month,a Pennsylvania teenager was indictedafter investigators said he tried to help individuals travel to the Middle East to join the Islamic State (ISIS) group.Faisal Mohammad, a California college student who  stabbed four people late last year was reported to have been carrying an image of the black flag of ISIS as well as a handwritten manifesto with instructions to behead a student and multiple reminders to pray to Allah.

Source: 23-year-old Muslim arrested for planning attack in Milwaukee