Anger over U.S. military operations abroad was the most commonly cited factor in motivating "homegrown terrorists," according to a secret FBI study reviewed by The Intercept on Tuesday. The study, conducted in 2012 and titled Homegrown Violent Extremists: Survey Confirms Key Assessments, Reveals New Insights About Radicalization, also found that there was no clear path to "radicalization" and that predicting future attacks remained effectively impossible.