Attacks Sept. 11 on the U.S. consulate in Benghazi, Libya, left the U.S. ambassador to Libya and members of staff dead.
U.S. Secretary of State Hillary Clinton called on the FBI to investigate the attack. This week, she suggested al-Qaida in the Islamic Maghreb was likely behind the raid. The White House expressed similar sentiments.
U.S. Secretary of Defense Leon Panetta said al-Qaida was very active in North Africa.
He said it was "pretty clear" that the attack in Benghazi was an act of terrorism.
"What terrorists were involved I think still remains to be determined by the investigation," he said. "But it clearly was a group of terrorists who conducted that attack against that facility."
U.S. officials who have suggested the Benghazi raid was an act of terrorism provided little proof to back the claims. Libyan militant group Ansar al-Sharia was named as a likely suspect, though its commander denied responsibility in an interview with the BBC shortly after the attack.