A US aircraft carrier and its escort of two cruisers have arrived off the Philippines coast to help communities devastated by Typhoon Haiyan.
The top US commander in the Philippines told the BBC that US military support would be on an unprecedented scale.
Officials have begun burying some typhoon victims in mass graves. The confirmed death toll stands at more than 2,300 but is likely to rise.
The UN says some 11 million people have been affected by the typhoon.
With images of the suffering flashed around the world, a huge international aid effort has swung into operation.
Philippine Health Minister Enrique Ona told the BBC that international criticism of the government’s relief efforts was “unkind”.
He said the final death toll was likely to be “significantly lower” than an early estimate of 10,000, but warned that it was unlikely all victims would be identified.
The USS George Washington will expand search-and-rescue operations and provide a platform for helicopters to move supplies, the White House said.
Two US destroyers are already in the Philippines and other US vessels are expected to arrive in about a week, the US Navy said.
On Wednesday the US also ordered the activation of a hospital ship, the USNS Mercy. However, if deployed, it would not reach the Philippines until December.
The UK government is sending the aircraft carrier HMS Illustrious, more than £20m ($32m) in aid, a team of medical experts and an RAF transport aircraft.
US Marine Brigadier General Paul Kennedy told BBC Radio 5 live that the US aid effort was being stepped up to a level that has “probably never been applied” to a humanitarian crisis.
He said the arrival of the USS George Washington would triple the number of available helicopters, which can also deliver hundreds of thousands of gallons of water every day.
Other countries have also pledged help in the shape of financial aid, relief supplies or emergency teams.
Japan is also preparing to send up to 1,000 troops as well as naval vessels and aircraft, Defence Minister Itsunori Onodera said.
China – which is engaged in a territorial dispute with the Philippines – is sending 10m yuan ($1.6m; £1m) in relief goods.
Its initial pledge of $200,000 (£120,000) from the government and Chinese Red Cross combined drew criticism in US media, but was also condemned by some Chinese internet users as excessive.
Orla Fagan, at the UN’s Humanitarian Affairs office in Manila, said that after a slow start, the aid effort was now accelerating.
“People are angry, they are distressed, they are traumatised, and we are trying to get this stuff out to them,” she said.
Typhoon Haiyan, one of the most powerful storms ever recorded on land, hit the Philippines last Friday.
UN humanitarian chief Valerie Amos, visiting the devastated city of Tacloban, said the situation was desperate with residents left without food or fresh water for five days.
Aid was now getting in, she said, but “I do feel that we have let people down.”
Tacloban’s airport was left in ruins by the storm, but in recent days US military planes have been arriving with World Food Programme supplies. A French-Belgian field hospital has also been set up.
Manila has sent troops to Tacloban to keep law and order, but correspondents say there is a growing sense of panic.
In some areas survivors have resorted to digging up water pipes and extracting fuel from reservoirs at petrol stations.
Health experts have warned that the worst-affected areas are entering a peak danger period for the spread of infectious diseases.