The U.S. launched a series of drone attacks in Yemen to curb a perceived growing terror threat due to political chaos in Yemen. Since December 2009, U.S. strikes in Yemen have been carried out by the U.S. military with intelligence support from the CIA. The drone strikes are protested by human-rights groups who say they kill innocent civilians, and that the U.S. military and CIA drone strikes lack sufficient congressional oversight, including the choice of human targets suspected of being threats to America. Controversy over U.S. policy for drone attacks mushroomed after a September 2011 drone strike in Yemen killed Anwar al-Awlaki and Samir Khan, both U.S. citizens. Another drone strike in October 2011 killed Anwar's teenage son, Abdulrahman al-Awlaki.