U.S. President Barack Obama said Thursday the seven Central Intelligence Agency (CIA) employees killed by a suicide bomber in eastern Afghanistan come from a “long line of patriots” whose courageous service has helped prevent terrorist plots and save lives. In a letter to CIA employees released by the agency, Obama said the United States would not be able to maintain its freedom and security without their service. He also noted that the intelligence agency has been tested “as never before” since the September 11, 2001 terror attacks. Obama, who is in Hawaii for the holiday's, wrote to tell CIA staff they “have helped us understand the world as it is, and taken great risks to protect our country.”