PEARL HARBOR, Hawaii • Veterans from Pearl Harbor observed the 70th anniversary of the attack Wednesday with a solemn ceremony at the site of the Japanese bombing, as an aging and dwindling group of survivors announced that it would disband at the end of the month.

"It was time. Some of the requirements became a burden," William Muehleib, president of the Pearl Harbors Survivors Association, said after the ceremony. He also cited poor health among the group's 2,700 members, adding that most of the survivors have realized there are other things they'd like to do at their age.

Survivors of the Japanese attack on Dec. 7, 1941, will be able to attend future commemoration ceremonies on their own. About 3,000 people, including Navy Secretary Ray Mabus and military leaders, attended this year's anniversary at a site overlooking the sunken Arizona and the white memorial that straddles the battleship.

Muehleib said there are about 7,000 to 8,000 Pearl Harbor survivors. Local chapters of the group will function as long as they have members and survivors can gather socially, but they will no longer have a formal, national organization.

The group's announcement came as President Barack Obama hailed veterans of the bombing in a statement proclaiming Wednesday as "National Pearl Harbor Remembrance Day." The attack brought the United States into World War II.

"Their tenacity helped define the Greatest Generation, and their valor fortified all who served during World War II. As a nation, we look to December 7, 1941, to draw strength from the example set by these patriots and to honor all who have sacrificed for our freedoms," he said.

Also this week, five ash scattering and interment ceremonies are being held for five survivors whose cremated remains are returning to Pearl Harbor after their deaths.

On Tuesday, an urn containing the ashes of Lee Soucy was placed on his battleship, the Utah, which is lying on its side near the place where it sank. The ashes of Vernon Olsen, who was on the Arizona during the attack, will be placed on his ship late Wednesday.

The U.S. lost 12 vessels that day, but the Arizona and the Utah are the only ones still sitting in the harbor.

The ashes of three other survivors will be scattered in the water in separate ceremonies this week.

Utah survivor Gilbert Meyer said he comes back each year to see his shipmates entombed in the battleship which rests not far from where it sank off Ford Island.

Meyer, 88, recalled his ship rolling over after being hit by a torpedo and seeing Japanese planes dropping bombs. When the planes began showing machine gun fire, he knew it was time to move.

"That really got my attention, so I got in the water and swam ashore," he said.