Panetta told the Senate Armed Services Committee plans call for adding 35 new Marine security guard contingents during the next two or three years, The New York Times reported.
"We are working with [the State Department] now to identify specific locations for the new detachments," Panetta said during a hearing on the Sept. 11, 2012, attack on a U.S. diplomatic facility in Benghazi, Libya, in which U.S. Ambassador to Libya Christopher Stevens and three other Americans were killed.
Although Marine security detachments are in place at 152 diplomatic facilities around the world, none was stationed at the Benghazi facility when it was besieged in what the Obama administration has characterized as a terrorist attack.
Panetta told the Senate committee the U.S. military did not have advance intelligence indicating an assault in Benghazi was imminent and no U.S. forces were close enough to Benghazi to be sent there quickly once the attack began.
"The Department of Defense was prepared for a wide range of contingencies, but unfortunately there were no specific indications of an imminent attack on U.S. facilities in Benghazi," he said. "Without adequate warning, there was not enough time given the speed of the attack for armed military assets to respond."
He said Marines guarding diplomatic facilities would have a broader mandate, including "expanded use of non-lethal weapons, and additional training and equipment, to support the Embassy Regional Security Officer's response options when host nation security force capabilities are at risk of being overwhelmed."