Thailand is to allow the US to fly surveillance planes through its airspace to help identify boats carrying migrants adrift in south-east Asian seas.
"Yes, we are permitting it, it is starting today," said Thailand's Deputy Prime Minister General Tanasak Patimapragorn.
The flights will help the migrant crisis that is rapidly developing in the region.
American authorities have said that the thousands of migrants adrift in Southeast Asian seas are in need of urgent rescue, as countries gathered in Bangkok to discuss a crisis that's overwhelming the region.
"We have to save lives urgently," US Assistant Secretary of State Anne Richard told reporters on her way into the meeting.
Thousands of migrants are adrift, abandoned by traffickers on overcrowded boats after a Thai crackdown made it too risky for them to continue using trafficking routes through Thailand.
The US has asked Thailand to fly surveillance flights from Thai bases to identify boats carrying migrants, Richard said, but has yet to get the nod from Thai authorities.
She added America is operating similar flights from Malaysia.
Malaysia's prime minister says his country will conduct search and rescue operations for thousands of stranded migrants.
More than 3,000 people, including Rohingya Muslims fleeing persecution in Burma and Bangladeshis trying to escape poverty, have arrived in overcrowded boats on the shores of Indonesia, Malaysia and Thailand.
Najib Razak tweeted that he had ordered his country's navy and coastguard "to conduct search and rescue efforts (for) Rohingya boats. We have to prevent loss of life".
Malaysia and Indonesia have said they will provide temporary shelter to migrants, but have appealed to the international community for help in resettling them.
Indonesia and Malaysia will provide temporary shelter to thousands of migrants who had been stranded at sea, marking the first breakthrough in the humanitarian crisis confronting south-east Asia.
Most of the migrants are the persecuted Rohingya Muslim minority from Burma and others are Bangladeshis fleeing poverty.
The agreement came as more than 430 migrants who had been stranded at sea for months were rescued and taken to Indonesia.
"Indonesia and Malaysia agreed to continue to provide humanitarian assistance to those 7,000 irregular migrants at sea," Mr Anifah told reporters.
He said the two countries "also agreed to provide them temporary shelter provided that the resettlement and repatriation process will be done in one year by the international community".
Hundreds of Rohingya and Bangladeshi migrants have been brought to shore in Indonesia's northwestern Aceh province, Reuters reported, citing a search and rescue official.
"In total we found around 500 people out at sea and they are being brought to land in smaller boats," Khairul Nova, of the national search and rescue agency, said.
Over 350 migrants have been brought to shore by local fishermen in the town of Kuta Binje and are being registered by immigration authorities, a witness told the news agency.
The latest group brought to shore adds to the over 2,000 who have managed to land in Indonesia and Malaysia after weeks of drifting in the Andaman Sea with little food or water.
More than 100 migrants have been brought to shore by fishermen in Indonesia's northwestern Aceh province, Reuters reported, citing a search and rescue official.
"Nearly 400 more have been sighted at sea and fishermen are attempting to bring them to land," Khairul Nova, of the national search and rescue agency, said.
Nova said the Rohingya and Bangladeshi migrants had landed in the town of Kuta Binje in Aceh.
The latest group brought to shore adds to the nearly 1,400 who have managed to land in Indonesia after weeks of drifting in the Andaman Sea with little food or water.
Malaysia has launched a series of high-level talks with its neighbours to seek a solution to the deepening refugee crisis in the region.
The UN High Commissioner for Refugees believes there are up to 8,000 migrants on "boats in the Andaman Sea" trying to reach land.
Malaysian foreign minister Anifah Aman met with his counterpart from Bangladesh ahead of meetings with the Indonesian and Thai foreign ministers in the coming week.
Malaysia is the current chair of the 10-nation Association of Southeast Asian Nations, which has been criticised for long ignoring the plight of Rohingya Muslims fleeing persecution in Burma.
Myanmar has said it is not to blame for the escalating migrant crisis in the Andaman Sea.
More than 2,000 migrants have arrived in Thailand, Malaysia and Indonesia in recent weeks, with thousands more believed to be currently adrift at sea after tougher action on human traffickers led some captains and smugglers to abandon their boats.
While some are Bangladeshi economic migrants, many of those aboard the boats are Rohingya Muslims fleeing persecution in Myanmar.
However, Major Zaw Htay, director of the office of the country's president, told the Associated Press: "We will not accept the allegations by some that Myanmar is the source of the problem."
He also said that Myanmar's government would not attend a meeting called by Thailand on the crisis "if 'Rohingya' is mentioned on the invitation", accusing governments of trying to divert attention from their own human smuggling and slavery problems by blaming his country.
An official for the UN High Commissioner for Refugees has said that up to 8,000 people are on "boats in the Andaman Sea".
UNHCR official Jeffrey Savage said: "We understand there as many as 8,000 or more we don't really know who are still on boats out in the Andaman Sea.
"UNHCR has called on the international community particularly the countries in the region to undertake a massive search search and rescue operation to bring those people to shore, give them the same kind of assistance and humanitarian supports that we giving in this groups."
A boat full of migrants has been towed out to sea towards Indonesia and away from its southern islands in the Andaman Sea by the the Thai navy, a witness said. The boat was being towed southwest by Thai navy patrol boat number 911, the witness told Reuters.
The navy was unable to confirm if the boat was the same one it towed out of Thai waters on Friday. Thousands of migrants are adrift in Southeast Asian waters, abandoned by people smugglers in the Andaman Sea following a Thai crackdown on human trafficking.