At least three dozen people in the U.S. suspected of ties to the Islamic State were under heavy electronic or physical surveillance even before the Paris attacks, but most of those under investigation here never traveled to Syria to fight alongside the Islamic State or receive training from it, reports the New York Times. In many ways, that makes the American investigations even harder. Those under investigation typically have little terrorism expertise or support from a cell, which makes thwarting an Islamic State-inspired attack here less like stopping a traditional terrorist plot and more like trying to prevent a school shooting.
This year, American counterterrorism officials began focusing their resources on Americans — known as homegrown violent extremists — after the Islamic State began using social media to urge its sympathizers in the U.S. to plot violence here rather than travel to Syria. “They're targeting the school-shooter types, the mentally ill, people with dysfunctional families and those struggling to cope with different issues,” said a law enforcement official.