The U.S. Navy has deployed an amphibious transport ship to the Mediterranean, where five destroyers are already in place for possible missile strikes on Syria.
The USS San Antonio, with several helicopters and hundreds of Marines on board, is "on station in the Eastern Mediterranean" but "has received no specific tasking," said U.S. the defense was quoted by AFP.
Unlike the destroyers deployed to the area, the San Antonio carries no Tomahawk cruise missiles but can ferry up to four helicopters and is designed to bring Marines ashore by chopper or landing craft.
No amphibious landing is in the works, however, as President Barack Obama has ruled out any "boots on the ground" if the US takes military action against the Syrian regime.
There are five destroyers off the coast of Syria, the USS Stout, Mahan, Ramage, Barry and Graveley that are ready to fire cruise missiles if Obama gives the order.