Barack Obama has stressed the "critical" importance of the Asia-Pacific region to the future of the US during his first foreign trip since his re-election.
The US President flew into Bangkok for the first stop of a three-country tour which will include Cambodia and Burma.
Speaking at a news conference with the Thai Prime Minister Yingluck Shinawatra, Mr Obama stressed the important role the region will play in shaping US interests over the coming century.
"Asia is my first foreign trip since our election in the United States, and Thailand is my first stop," Mr Obama said.
"This is no accident. As I've said many times, the United States is and always will be a Pacific nation.
"As the fastest growing region in the world, the Asia-Pacific will shape so much of our security and prosperity in the century ahead, and it is critical to creating jobs and opportunity for the American people.
"That's why I've made restoring American engagement in this region a top priority as president."
Mr Obama also met the Thai King, Bhumibol Adulyadej, who is in hospital where he has been recovering from an illness since September 2009.
Mr Obama calls himself the "Pacific President" and has pledged to focus significant attention on the Asia-Pacific region.
It is therefore no surprise that his first foreign trip is here.
The US is seeking to counter China's increasing clout in the region. The US government has said that 60 per cent of the US naval forces will be based in the region by 2020.
As if to underline America's commitment to the region, the US Defence Secretary is currently on his fourth trip to Asia this year.
Thailand is the United States' longest standing ally in the region. The US sees it as vital in helping it pivot attention towards Asia and boost ties with the fastest growing region on the planet.
The main focus of the trip will be to Burma on Monday.
Mr Obama will become the first US president ever to visit the country. The visit is a key indicator that Washington believes Burmese government reforms are genuine and continuing.
During the news conference, Mr Obama defended his decision to go to Burma.
"This is not an endorsement of the Burmese government," he said.
"This is an acknowledgement that there is a process underway inside that country that even a year and a half, two years ago, nobody foresaw."
He will meet both President Thein Sein and opposition leader Aung San Suu Kyi. On Friday, Washington announced it had lifted a ban on the import of goods from the country.
The president's visit follows a trip by US Secretary of State Hillary Clinton to the country in December 2011 and a visit by British Prime Minister David Cameron in April 2011.
The US President's Asian tour will end in Cambodia where he will attend a meeting of the Association of South East Asian Nations (Asean).
The leaders of 16 southeast Asian countries will attend, as well as the Russian President Vladimir Putin, the outgoing Chinese Premier Wen Jiabao, the Japanese Prime Minister Yoshihiko Noda, the Australian Prime Minister Julia Gillard and the Indian Prime Minister Manmohan Singh.
In Burma, despite the recent reforms, sectarian clashes between Muslims and Buddhists have killed more than 180 people and destroyed the homes of more than 100,000.
The government has been criticised for not having done enough to stop the violence in the coastal Rakhine State.