Bangkok - President Barack Obama on Sunday defended his trip to Myanmar, also known as Burma, insisting that the visit today is "not an endorsement" of the nation's long-repressive leadership but rather an acknowledgment that the country is making progress toward reform.

"I don't think anybody is under any illusion that Burma has arrived, that they're where they need to be," Obama said at a joint news conference with Thai Prime Minister Yingluck Shinawatra to kick off his three-country Asia trip.

"I'm not somebody who thinks the United States should stand on the sidelines and not get its hands dirty when there's an opportunity for us to encourage the better impulses inside a country," Obama said.

Human rights activists have denounced Obama's decision to become the first U.S. president to visit the Southeast Asian nation, which is attempting to emerge from decades of authoritarian military rule. Critics of the trip said the White House should not reward Myanmar prematurely, citing escalating ethnic violence against the nation's Muslim minority that has killed hundreds and displaced as many as 100,000.

The Obama administration has bet heavily on Myanmar's continued commitment to reform, appointing Ambassador Derek Mitchell to the country in June and sending Secretary of State Hillary Rodham Clinton for a visit there last December.

Clinton, who was in Bangkok with Obama, will fly with him aboard Air Force One into the historic former capital of Rangoon today. Clinton has said she will leave her post as soon as a successor is found, and this is their final foreign trip together, White House officials said.

"If we waited to engage until they had achieved a perfect democracy, my suspicion is that we'd be waiting an awful long time," Obama said of Myanmar. "One of the goals of this trip is to highlight progress that has been made, but also voice that much greater progress needs to be made in the future."

Obama opened his first post-election foreign trip by paying a visit to Thailand's King Bhumibol Adulyedaj, 84, a revered figure who is severely ill and hospitalized, and touring the Wat Pho Royal Monastery before joining Yingluck in a formal welcome dinner at the Government House. The president lavished praise on his host country, saying Thailand's 180-year relationship with the United States makes it "our oldest ally" in Asia.

The Obama administration is using the Asia trip, which includes a final stop in Cambodia for the East Asia Summit, as another step in its "pivot to Asia" aimed at counterbalancing China's growing influence in the region.

During the news conference, Obama responded to a question about whether Beijing offered Thailand a less messy path toward prosperity than politically gridlocked Washington, by saying that "democracy is a little messier than alternative systems of government, but that's because democracy allows everybody to have a voice."

He added that "the notion somehow that you can take shortcuts and avoid democracy, and that that somehow is going to be the mechanism whereby you deliver economic growth, I think is absolutely false."

White House aides said the president would announce today that the United States will re-establish in Myanmar a U.S. Agency for International Development mission and offer the country up to $170 million in new foreign aid over the next two years that would be conditional on the government continuing toward democratic reforms.

"Everything we do is going to be based upon the principle of action for action and partnership with the Burmese," said one senior administration official, speaking on the condition of anonymity to preview the president's trip.

Although the trip takes Obama out of Washington just as negotiations over the looming "fiscal cliff" heat up, he hoped some good fortune in Thailand would rub off on his domestic prospects.

"We're working on this budget; we're going to need a lot of prayer for that," Obama joked to the head Buddhist monk who was guiding him and Clinton on a private tour of the Royal Monastery.

"I always believe in prayer," Obama said in his news conference, after a reporter mentioned the joke during a question. "If a Buddhist monk is wishing me well, I'm going to take whatever good vibes he can give me to try to deal with some challenges back home. I'm confident that we can get our fiscal situation dealt with."