"You and I share the view that the U.S.-China relationship is one of the most important bilateral relationships in the world," Wen added, even as he acknowledged differences on issues.
Obama's talks with Noda and with Wen were likely to be his last bilateral meetings with both men.
Noda dissolved his country's parliament last week, setting the stage for new elections his party is unlikely to win. And China is undergoing its first leadership transition in a decade, with Wen and President Hu Jintao stepping down to clear the way for new leaders in the country's Communist Party.
Obama has added the Asia summit to his annual list of high-priority international meetings as he seeks to expand U.S. influence in the region.
A welcome sign did greet Obama upon his arrival — but it heralded Wen, not the American president.
Human rights groups fear that because Obama delivered his condemnation of Hun Sen in private, government censors will keep his words from reaching the Cambodian people. And they worry the prime minister will then use Obama's visit to justify his grip on power and weaken the will of opposition groups.
"If Hun Sen's narrative about this visit is allowed to gel, it will create a perception that the United States and other international actors stand with Hun Sen, and not with the Cambodian people," said John Sifton, Asia director at Human Rights Watch. "It will be a tremendous blow to Cambodians who challenge his rule."
Obama's visit to Myanmar was also viewed critically by some international organizations, which saw the trip as a premature reward for a country that still holds political prisoners and has been unable to contain ethic violence.
Aware of that criticism, Obama tempered some of his praise for Myanmar during his six-hour visit. He underscored that the reforms that have taken hold over the past year are "just the first steps on what will be a long journey."
Perhaps the sharpest calls for caution came from Suu Kyi, Myanmar's longtime democracy champion. After meeting with Obama at the home where she spent years under house arrest, she warned that the most difficult part of the transition will be "when we think that success is in sight."
"Then we have to be very careful that we're not lured by the mirage of success," Suu Kyi said, speaking with Obama by her side.
Obama will return to Washington before dawn Wednesday, in time for the ceremonial pardoning of the Thanksgiving turkey.
Associated Press writers Jim Kuhnhenn and Grant Peck contributed to this report.
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