This booking photo taken in April and released by the Hamilton County, Tenn., sheriff's office shows a man identified as Mohammod Youssuf Abdulazeez after being detained on suspicion of a driving offense. AP hide caption

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FBI Director James Comey testifies that Congress should require digital encryption programs to allow access by law enforcement. The issue pits privacy against public safety. Carolyn Kaster/AP hide caption

itoggle caption Carolyn Kaster/AP

An Islamic State fighter holds holds a rifle and the group's flag shortly after capturing the northern Iraqi city of Mosul in June 2014. Dozens of Americans have been accused of planning or heading off to the Middle East to join the group. Their individual cases are on the chart below. Reuters/Landov hide caption

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A member of Iraq's government forces battling Islamic State fighters in Anbar province earlier this month. Haidar Hamdani/AFP/Getty Images hide caption

itoggle caption Haidar Hamdani/AFP/Getty Images