WASHINGTON -- With expectations rising that the Obama administration might order a retaliatory strike against the Islamist extremists who attacked and killed four Americans in Libya Tuesday, the U.S. military is taking a decidedly cool stand, at least in public.

As previously reported, a 50-man Marine Corps Fleet Anti-Terrorism Security Team (FAST) element was deployed Wednesday to Libya, Pentagon spokesman George Little confirmed in a briefing at the Pentagon Thursday. In addition, "sufficient numbers" of Marines have been sent into the region to reinforce embassy security, he said.

But Little declined to detail U.S. movements in the Mediterranean or to confirm that two destroyers had been sent into the region. The United States maintains a fleet of warships in the Mediterranean, but Little said none have been assigned any specific mission related to the Libya attack.

Little also declined to say whether additional military assets were being moved into the region, or whether the FAST detachment had been sent to Benghazi, where the U.S. consulate was overrun Tuesday and U.S. Ambassador Christopher Stevens and three other Americans were killed. No Marines had been assigned to protect the consulate in Benghazi despite the known presence of al Qaeda-linked groups there, he confirmed.

U.S. Marines are protecting the American embassy in Sana, Yemen, which was stormed by mobs that tore down and burned the American flag during a pitched battle Thursday. Little said he could not say what part the U.S. Marine security detail at the embassy played in repelling the attackers.

Little said the Defense Department continues to have strong bilateral relationships with the governments of Libya and Egypt, where anti-U.S. protest continued for the third day.