Obama had provoked China when meeting President Hu Jintao last week during the Asia-Pacific Economic Cooperation summit in Hawaii, saying Americans were "frustrated" and "impatient" at the pace of change in Beijing's economic policy.

Hu responded by saying a big rise in the yuan would not help the US, and that the US should not blame its trade deficit and unemployment on China.

In other signs of increased US attention to Asia during Obama's nine-day trip to the region that ended Saturday, he announced that the US will post up to 2,500 Marines in Australia from mid-2012, as a "commitment to the entire Asia Pacific region".

The move, however, drew concern from neighboring countries, with Singapore, Malaysia and Indonesia saying they were wary of new risks.

On Wednesday, US Secretary of State Hillary Clinton promised in Manila that the US will give the Philippines a second Coast Guard cutter virtually for free to help the US ally. Tension had escalated between Beijing and Manila this year on the South China Sea issue.

"We have a very complicated and quite substantial relationship with China across the board," Donilon told reporters on Saturday. He downplayed tensions between the two powers, saying they have also found vast areas of agreement.

China's Assistant Foreign Minister Liu Zhenmin also adopted a mild tone when asked about Washington's new focus on Asia, saying China is keen to cooperate with the US in the region.

Reuters said in a commentary on the same day that Obama's sharpened tone toward China was part of "a strategy that might help him counter criticism from Republican hopeful Mitt Romney, who has accused Obama of being willing to only 'whisper' to Beijing about US trade concerns".

"Historically speaking, criticizing China would not definitely win points for US president candidates. But it is a safe strategy that definitely would not lose points," Niu said.

Wen also met with the prime ministers of Australia and Singapore later on Saturday.

Australian Prime Minister Julia Gillard said before the meeting she would explain that increased US military training on Australian territory poses no threat to China. She said it was possible for Australia to have an ally in Washington and a friend in Beijing.