WASHINGTON – The U.S. military is determined to position small, quick reaction forces closer to global crises after the rapid assault on the U.S. diplomatic mission in Libya last September kept U.S. armed forces from responding in time to save four Americans.

Defense Secretary Leon Panetta and Army Gen. Martin Dempsey, the chairman of the Joint Chiefs of Staff, told Congress on Thursday that they moved quickly to deploy commando teams from Spain and Central Europe on Sept. 11, the chaotic day of the assault on the U.S. installation in Benghazi, but the first military unit didn’t arrive until 15 hours after the first of two attacks.

“Time, distance, the lack of an adequate warning, events that moved very quickly on the ground prevented a more immediate response,” Panetta said in what likely was his last Capitol Hill appearance before stepping down as Pentagon chief.