Mrs. Clinton, in a letter to Congress, outlined a number of steps the department is taking to improve security, including hiring hundreds of additional Marine guards for high-risk embassies and consulates around the world.

In an apparent gesture of support for the American diplomatic corps, President Obama — speaking at a diplomatic reception at the State Department on Wednesday night — praised the department’s personnel, who he said often worked “at great risk.”

Another issue that might be raised and that was largely skirted by the panel, concerns what role the American military should play in protecting diplomats abroad.

The Pentagon had no forces that could be readily sent to Benghazi when the crisis unfolded. The closest AC-130 gunship was in Afghanistan. There are no armed drones thought to be within range of Libya. There was no Marine expeditionary unit — a large seaborne force with its own helicopters — in the Mediterranean Sea. The Africa Command, whose area of operation includes North Africa, also did not have on hand its own force able to respond rapidly to emergencies — a Commanders’ In-Extremis Force, or C.I.F. Every other regional command had one at the time.

The Defense Department has repeatedly declined to say whether the Africa Command requested that any of these forces be on hand during the anniversary of the Sept. 11, 2001, terrorist attacks. Nor has it said whether Defense Secretary Leon E. Panetta or Gen. Martin E. Dempsey, the chairman of the Joint Chiefs of Staff, gave any thought to moving forces in the region as a precaution.

The unclassified version of the Benghazi report concluded that “there simply was not enough time given the speed of the attacks for armed U.S. military assets to have made a difference.” But the report did not address whether it would have been prudent to station quick-reaction forces in the region or whether the United States would have been in a position to quickly respond militarily had Ambassador Stevens been kidnapped and the crisis had dragged on, as was initially feared.