Updated

A massive American military relief operation picked up steam on Monday with U.S. helicopters dropping off cartons of food aid in Sumatra and U.S. warships with 2,200 Marines arriving in the Malacca Straits to begin ferrying supplies to the tsunami-battered island.

To get a firsthand look at the devastation, a U.S. delegation including Secretary of State Colin Powell (search) and Florida Gov. Jeb Bush (search) on Monday begins a trip that includes stops in Thailand, Indonesia and perhaps Sri Lanka.

Meanwhile, searchers all but gave up hope of finding more survivors from last week's killer earthquake and tsunami (search), with authorities saying Monday that thousands listed as missing were presumed dead. The world turned its full attention to getting food and water to the living.

Confirmed deaths from the disaster reached 137,321 after hardest-hit Indonesia increased its death toll to 94,081. Aid agencies have said the death toll was expected to hit 150,000. Sri Lanka, India and Thailand said they were almost ready to give up on more than 15,000 still unaccounted for.

The Dec. 26 tsunami struck the region without any advance notice, and Indonesia announced plans Monday to work with its Asian neighbors to establish a system to warn coastal communities before potentially deadly waves hit.

Aid workers, meanwhile, were trying to help the millions of people displaced and devastated by the loss of family and friends put their towns and villages back together.

On Monday, the USS Bonhomme Richard and two other warships carrying a Marine expeditionary unit, dozens of helicopters and tons of supplies steamed into the Indian Ocean to join in relief operations off the hard-hit northwest coast of Sumatra.

Later this week, the group was to begin operations off the shores of Sri Lanka.

"We've been racing across the ocean," said Rear Adm. Chris Ames, commander of the strike force.

Ames acknowledged that the situation in Sri Lanka remains unclear, and that the mission for the Marines is still developing. He said the Marines' primary responsibilities would include ferrying food and medical supplies to villages in need. He also stressed that having "boots on the ground" would bring badly needed manpower for constructing temporary shelters, clearing roads and operating water purification equipment.

"We know a lot more today than we did yesterday," he said. "But we're not waiting for a perfect picture. There's so much to be done."

The ships are part of one of the largest U.S. military missions in Asia since the Vietnam War ended in 1975. The aircraft carrier USS Abraham Lincoln and its battle group are operating off northern Sumatra, the hardest hit area, and U.S. airlift operations are being flown out of Utapao, a base in Thailand used to stage bombing missions in the Vietnam era.

Also on Indonesia's Sumatra island, U.S. helicopters dropped off cartons of food aid donated by Singapore schools. Flying missions along a 120-mile stretch of Sumatra coastline, the extent of the damage from the Dec. 26 earthquake and tsunami became eerily obvious.

At one point, the choppers flew low over what appeared to be a fishing flotilla off the coast in glassy seas. Some boats were clearly damaged, while others appeared to have emerged from the disaster unscathed. But there was no sign of life at all.

At Karim Rajia, two helicopters dropped off 1,800 pounds of soup and biscuits there in cartons stenciled: "Our deepest condolences to the brothers and sisters in Aceh. May god be with them. Love from the teachers and students of Singapore."

Several people were taken off on stretchers on the USS Abraham Lincoln after the U.S. military got permission from Jakarta on Sunday to pick up survivors in bad shape.

"I'd much rather be doing this than fighting a war," said helicopter pilot Lt. Cmdr. William Whitsitt of Great Falls, Mont.

The aid deliveries were a mere drop in an ocean of need — but priceless nonetheless, said Indonesian military spokesman Ahmad Yani Basuki.

"They've helped us reach places we have not had the time, or manpower, or equipment to go to," said Basuki, noting that Americans had helped clear helicopter landing spaces for the arrival of future supplies. "It really speeds up the distribution of aid to (Sumatra's) west coast."

International donors, meeting this week in Indonesia, have so far pledged about $2 billion. But the needs of disaster victims remain enormous, and relief efforts have been hampered by the destruction of roads, ports and airfields.

As the relief effort continued to build, affected nations were also working to ensure that nothing on the scale of last week's disaster would happen again.

Indonesian President Susilo Bambang Yudhoyono on Monday said his nation would join in an international effort to set up an early warning system to limit the loss of life in any similar catastrophe in the future.

"This would be a kind of pre-emptive measure," he told reporters.

Yudhoyono didn't specify how many countries would be involved, but regional leaders were expected to endorse establishing such a system during a donors' conference Thursday in Jakarta, organized through the 10-member Association of Southeast Asian Nations.

Across the affected region, hope was fading by the hour for the tens of thousands still missing.

"There is very little chance of finding survivors after seven days," said Lamsar Sipahutar, the head of the search team in Indonesia. "We are about to stop the search-and-rescue operations."

In Sri Lanka, N.D. Hettiarachchi, director at the National Disaster Management Center, said nearly 17,000 people were injured and almost 1 million people had been displaced and were living in temporary camps at schools and religious places.

Children accounted for 40 percent, or 12,000, of the deaths in Sri Lanka, officials said. But without bodies to mourn over, many parents find it hard to believe their children are dead. Some were buried in mass graves, before parents were told. Many were swept out to sea.

Day after day parents come at dawn and wander the beach in the devastated districts of Ampara and Batticaloa.

"They believe their kids are alive and the sea will return them — one day," UNICEF chief Carol Bellamy said on Sunday, after touring this island country's tsunami-devastated shore.

In New York, U.N. humanitarian chief Jan Egeland said 1.8 million people in tsunami-hit countries would need food aid and that figure could rise. It would take about three days to get food to 700,000 people in Sri Lanka but much longer to reach the one million hungry people in Indonesia, he said. He warned there were still difficulties in reaching survivors in Sumatra's Aceh province.