"We are here for a friendly visit and some R and R," said Cmdr. Bradley Martin, commanding officer of the Germantown.
The Department of Foreign Affairs said the visit "has nothing to do with the ongoing military action in Afghanistan."
Martin refused to say where his ship, which saw action in Operation Desert Shield and Operation Desert Storm 10 years ago, would go after the Philippines.
The 15,988-ton vessel carries 307 sailors and 456 Marines who will be allowed liberty at the Subic Bay Freeport, a former US naval station that was closed by the United States in 1992 after the Senate refused to renew its lease.
Martin said he is still evaluating "protection policies" for the American service members before allowing them on leave. He said he may allow about 15 Filipino crew members to visit their relatives.
The Olongapo police tightened security along two major roads leading to the port.
Martin said the ship came from a medical mission in East Timor and made a brief stop in Palau before the Philippines.
Last week, six US F-18 jet fighters and five US military transport planes stopped in the Philippines to refuel while en route from Japan to an undisclosed location to participate in US-led military action against Afghanistan.
Also last month, about 25 US military advisers spent two weeks in the country for talks on how the United States can help fight the extremist Abu Sayyaf.
The United States says the Abu Sayyaf has ties to Osama bin Laden, the chief suspect in the Sept. 11 terrorist attacks on New York and Washington. — Bebot Sison Jr.