Hint: it's not because we're free.

The final report, called "Homegrown Violent Extremists: Survey Confirms Key Assessments, Reveals New Insights about Radicalization," found "anger over U.S. military operations abroad was the most commonly cited motivation for individuals involved in cases of 'homegrown' terrorism,'" the Intercept reported.

The report acknowledges that "[o]nline relationships and exposure to English-language militant propaganda and 'ideologues' like Anwar al-Awlaki," who, along with his teenage son, was killed by a drone strike in 2011, were also "key factors" in the radicalization process.