US Navy's USS Carl Vinson aircraft carrier is seen anchored off the Manila bay, west of Manila May 15, 2011. The USS Carl Vinson is the ship where Osama bin Laden was given burial ritual after he was killed in a raid by US Navy Seals in Abbottabad, Pakistan. The Carl Vinson is escorted by the USS Bunker Hill, the USS Shiloh guided missile cruisers and the destroyer USS Gridley which arrived in Manila on Sunday for a four-day routine port call. [Photo/Agencies]

ABOARD THE USS CARL VINSON - US officials welcomed visitors Sunday to the USS Carl Vinson warship, from which Osama bin Laden's body was buried at sea, but did not discuss the ultra-secretive attack that killed him, reflecting America's concern over possible retaliation.

US defense officials were taking measures to ensure the security of the operatives involved in the May 2 assault on a walled fortress in Abbottabad, Pakistan, particularly the Navy SEAL team that killed the world's most wanted terrorist.

President Benigno Aquino III, accompanied by senior members of his Cabinet and military chief of staff, were flown to the massive aircraft carrier Saturday as it traveled toward the Philippines, a key Asian anti-terrorism ally.

A group of journalists were invited to tour and talk to sailors aboard the 97,000-ton Carl Vinson, which anchored off Manila along with three other warships on Sunday at the start of a four-day routine port call and goodwill visit.

During the 30-minute ferry ride to the Vinson, US Embassy spokeswoman Wossenyelesh Mazengia told about two dozen journalists that nobody aboard the carrier would talk about bin Laden. "No one on the Vinson is authorized to discuss any operational details that involve Osama bin Laden," Mazengia said. "I'm not trying to say you can't ask, you can."

Defense Secretary Voltaire Gazmin said Aquino and his entourage were given a tour of the warship and an exhibition of fighter jets landing and taking off from the Carl Vinson, including one flown by a Filipino-American pilot.

Aquino, at one point, sat on the cockpit of an F/A-18E Super Hornet fighter jet at a hangar bay as sailors snapped pictures. He talked and posed for souvenir pictures with many beaming Filipino-American sailors, Gazmin said.

But the one thing on everybody's mind - bin Laden's burial from the Carl Vinson just 12 days earlier - did not come up. US Navy officials did not touch the sensitive subject and Aquino's group saw it fit not to ask questions, Gazmin said.

"We did not ask for a briefing because it was too sensitive," Gazmin told The Associated Press on Sunday. "It was a friendly visit and we let it stay that way."

Gazmin, a retired general, said he was impressed by the stunning US commando night-time strike that got bin Laden, adding it showed the might of the American military force.

Foreign Secretary Albert del Rosario, who said it was his first time to set foot on an aircraft carrier, was impressed as war planes landed and were launched by catapults from the tarmac.

"You can feel the inherent power of these fighter jets," del Rosario said.

In impromptu remarks on the ship, Aquino reaffirmed the "historic, defense and cultural ties" between the United States and the Philippines, one of Washington's oldest and closest Asian allies, presidential spokesman Ricky Carandang said.

US special forces have been training and arming Filipino soldiers battling al-Qaida-linked militants in the southern Philippines since 2003.

The Carl Vinson came from the North Arabian Sea, where it had received a US SEAL team, which carried bin Laden's body after killing the long-wanted al-Qaida leader in a raid on his walled compound near a Pakistani military academy.

Pentagon officials have said that on the carrier, bin Laden's body was placed in a "weighted bag," an officer made religious remarks and the remains were put on a flat board and tipped into the sea.

Defense Secretary Robert Gates has said that during a recent meeting with members of the team that attacked bin Laden, they expressed concerns about the security of their families.

American officials agreed shortly after bin Laden was killed not to release any operational details on the commando assault, Gates said, but added "that fell apart - the next day."

"We are looking at what measures can be taken to pump up the security," Gates said.

The US Embassy in Manila said Carl Vinson's service members would take part in sports events, seminars and community assistance projects with their Philippine counterparts.

The visit will contribute about $4.65 million to the local economy from port fees and crew expenditures, the embassy said in a statement.

Philippine police have said they will step up security in Manila, where left-wing groups have threatened to stage protests against the US warship's visit.