An increase in terror incidents involving Islamic radicals who are U.S. citizens is vexing law enforcement officials and posing new questions about the roots of their radicalization.

U.S. foreign policy is largely directed by presidents, but Congress does have considerable influence, as this CFR Backgrounder explains.

The Bush administration’s approach to the detention and prosecution of prisoners held at Guantanamo Bay, Cuba, has been deemed unconstitutional by the U.S. Supreme Court. But the battle continues.

Sen. Barack Obama’s foreign policy team includes former State Department veterans and newcomers from academia who seek to reinvigorate U.S. diplomacy.