WASHINGTON - President Barack Obama hopes to demonstrate rising US clout in Asia on his first foreign trip since his re-election, with a tour of three countries including a once unthinkable stop in changing Myanmar.
Obama, who has cast himself as the first "Pacific president" with his roots in Hawaii and boyhood years in Indonesia, will head Saturday to longtime US ally Thailand and meet Asia's top leaders at a summit in Cambodia.
It will be the first trip by a US president spent entirely in Southeast Asia since the Vietnam War, part of Obama's effort to focus on the dynamic and largely US-friendly region where several nations worry about a rising China.
Obama in his first term launched a so-called "pivot" to Asia, which included greater military cooperation with Australia, Thailand and Vietnam and a plan to shift the bulk of the US navy to the Pacific by 2020.
"Continuing to fill in our pivot to Asia will be a critical part of the president's second term and ultimately his foreign policy legacy," Ben Rhodes, a deputy national security adviser, told reporters.
Tom Donilon, the national security adviser, said that Obama's trip showed that the United States was "not only rebalancing towards Asia; we're also rebalancing our efforts within Asia."
Donilon said it was "impossible to overstate Asia's importance" to the United States as the continent is expected to account for nearly half of the world's economic growth outside the United States through 2017.
"The fact is today that there is a tremendous demand and expectation of US leadership in the region," Donilon said.
Virtually no nation has seen a greater shift toward the United States under Obama than Myanmar. The nation formerly known as Burma was for years a close ally of China and treated as a pariah by Western nations.
Surprising skeptics, Myanmar launched reforms after its nominal end to nearly half a century of army rule last year. President Thein Sein, a former general, released political prisoners, opened dialogue with ethnic rebels and allowed once-confined opposition icon Aung San Suu Kyi to enter parliament.
Some human rights groups said that Obama should have waited, arguing that he could have dangled the prospect of a visit as leverage to seek more progress such as the release of remaining political prisoners estimated to number in the hundreds.
Danny Russel, Obama's top aide on Asia, countered: "This is not a victory celebration, this is as barn raising."
"We want to show the people of Burma that there are benefits to be had from the hard work and move some of the leaders off the fence and into the reform program," he said.
Thailand is the oldest US ally in Asia, famously offering elephants to Abraham Lincoln in the Civil War. But the kingdom has been consumed by internal disputes, which escalated in 2010 into violence that left more than 90 people dead.
Michael Green, who held Russel's position under former president George W. Bush, said that Thailand -- which proudly preserved independence even in World War II -- has historically kept a balance between major powers.
"Thailand has always sort of gone with the breeze. And China's very much the breeze now," said Green, the senior vice president for Asia at the Center for Strategic and International Studies.
The three nations that Obama will visit are "sort of the three troubled children of 'the pivot.' Each has a complicated relationship with the US and with China," Green said.
While few expect Thailand to shift wholescale to Beijing, Cambodia has been China's staunchest supporter in the 10-member Association of Southeast Asian Nations and was seen as scuttling an initiative on disputes in the South China Sea when Secretary of State Hillary Clinton visited for regional talks in July.
Obama will be the first sitting US president to visit Cambodia. Samantha Power, his adviser on human rights, said Obama was visiting for the East Asia Summit and was concerned about Cambodia's "very worrying" direction on rights.
On the summit's sidelines, Obama will meet China's outgoing premier, Wen Jiabao, and Prime Minister Yoshihiko Noda of Japan, whose relations with Beijing have grown tense due to territorial claims.
Japan is one of five treaty-bound US allies in the region. In a veiled reference to China, Donilon said Washington's alliances were a key asset.
When "you think about our competitors and possible competitors around the world, you come to the conclusion that no other nation in the world has the set of global alliances that the United States has," he said.
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