The United States dispatched two destroyers to Libya and deployed a Marine team to bolster security at its Tripoli embassy on Wednesday after its ambassador was killed in Benghazi.
The decision to move the ships and a roughly 50-member Marine unit to Libya comes after Washington's envoy and three other Americans were killed in an attack on the US consulate in Benghazi on Tuesday.
"Two destroyers are going to be in the vicinity of Libya but only as a precautionary measure," a senior US official said.
Pentagon spokesman George Little, while declining to comment on specific ship movements, said precautionary steps taken by the US military were "not only logical in certain circumstances" but also "the prudent thing to do."
President Barack Obama quickly ordered increased security at US diplomatic posts around the world, while denouncing the Benghazi assault, which coincided with the 11th anniversary of the September 11 attacks.
"The Marines are sending a FAST (Fleet Anti-terrorism Security Team) team to Libya," an official, who spoke on condition of anonymity, told AFP.
US Marines and private contractors are charged with safeguarding diplomatic posts abroad and it was unclear how the attackers managed to breach security.
The Fleet Anti-terrorism Security Teams, under the authority of the US Navy's chief of operations, were formed in 1987 to provide a fast response to security threats after a series of terror attacks in the 1970s and 1980s.
"These companies are called on to protect forces and installations when a heightened security threat requires it," states the unit's website.