Director of National Intelligence James Clapper, center, flanked by FBI Director Robert Mueller, left, and CIA Director John Brennan, right, listen during the Senate Intelligence Committee annual open hearing on worldwide threats on Capitol Hill in Washington, Tuesday, March 12, 2013. (AP Photo/Susan Walsh)

Photo by: Susan Walsh

Director of National Intelligence James Clapper, center, flanked by FBI Director Robert Mueller, left, and CIA Director John Brennan, right, listen during the Senate Intelligence Committee annual open hearing on worldwide threats on Capitol Hill in Washington, Tuesday, March 12, 2013. (AP Photo/Susan Walsh)