An unmanned U.S. Predator drone flies over Kandahar Air Field, southern Afghanistan, in 2010. A new report questions the U.S. policy of using armed drones abroad to carry out attacks on suspected terrorists. Kirsty Wigglesworth/AP hide caption

itoggle caption Kirsty Wigglesworth/AP

A U.S. drone in the sky over Kandahar Air Field in Afghanistan. Kirsty Wigglesworth/AP hide caption

itoggle caption Kirsty Wigglesworth/AP

Pakistani Prime Minister Nawaz Sharif met with President Obama at the White House on Wednesday. Dennis Brack/pool/Getty Images hide caption

itoggle caption Dennis Brack/pool/Getty Images

An American flag flying over Camp VI, where detainees are housed at the U.S. Naval Base at Guantanamo Bay. Bob Strong /Reuters /Landov hide caption

itoggle caption Bob Strong /Reuters /Landov

An unmanned drone armed with Hellfire missiles is shown over southern Afghanistan. A Hellfire missile fired from a drone was used in 2011 to kill an American in Yemen who the Obama administration says was an al-Qaida leader. Another American died in that attack, and a 16-year-old American was killed in a separate drone strike. Lt. Col. Leslie Pratt/AP hide caption

itoggle caption Lt. Col. Leslie Pratt/AP

John Brennan, President Obama's nominee to head the CIA, prepares to testify at his confirmation hearing before the Senate Intelligence Committee on Thursday. J. Scott Applewhite/AP hide caption

itoggle caption J. Scott Applewhite/AP