'Dozens' of Americans Believed to Have Joined Terrorists

Dozens of Americans have joined terrorist groups and are posing a threat to the United States and its interests abroad, the president's most senior adviser on counterterrorism and homeland security said Thursday in an interview with The Washington Times.

"There are, in my mind, dozens of U.S. persons who are in different parts of the world, and they are very concerning to us," said John O. Brennan, deputy White House national security adviser for homeland security and counterterrorism.