A top US commander said Tuesday that China has been entering fewer confrontations with its neighbors as he credited a firm line by Washington and its allies with changing Beijing's thinking.

President Barack Obama's administration has put a growing focus on Asia, stepping up trade ties and moving to maintain the strength of US forces in the region despite overall cuts to the military budget.

But Admiral Robert Willard, the outgoing head of the US Pacific Command which covers Asia, offered conciliatory words toward China in an appearance before Congress, saying that Beijing's rise was in the US interest.

"We've seen fewer confrontations in 2012 than we did in previous years. 2010 was quite landmark in terms of the confrontations" in the South China Sea, Willard told the Senate Armed Services Committee.

Willard said that China -- whose military spending has been sharply rising in recent years -- was still actively staking claims and challenging vessels that conduct operations in the hotly disputed waters.

But he said that "very strong statements" by Secretary of State Hillary Clinton, former defense secretary Robert Gates and members of the 10-nation Association of Southeast Asian Nations likely made an impression on China.

The public comments "I think took China aback and has caused them to reconsider that particular approach to their South China Sea claims," Willard said.

"They are endeavoring to continue to pursue it, but in a more thoughtful manner," Willard said in response to a question from the Senate committee.

Clinton, during a visit to Vietnam in July 2010, declared that the United States had an active interest in "freedom of navigation" in the South China Sea, where six nations hold competing and often overlapping claims.

The United States has also stepped up cooperation with Vietnam and the Philippines, which had both accused China of harassing their ships at sea, and plans to station troops in Australia.

The Obama administration has also stepped up pressure on trade, on Tuesday setting up a new agency to crack down on what the United States sees as unfair practices.

China has accused the United States of interference. Last month, Chinese state-controlled media said Beijing should impose sanctions on the Philippines over its offer to allow more US troops on its soil.

Some conservative critics of Obama have accused him of encouraging bellicose actions by China by putting too much focus on cooperation with the rising Asian power at the start of his term.

Mitt Romney, a Republican candidate hoping to challenge Obama in US elections in November, has said that Obama was a "near supplicant" to Beijing who has "only encouraged Chinese assertiveness and made allies question our staying power in East Asia."

Asked about China's rise, Willard told senators that Southeast Asian nations, despite their disputes with Beijing, wanted strong economic and other relations both with China and the United States.

"China's economic growth has benefited the entire region and has certainly benefited the United States and our economic ties to China. So I think it would be unfair to imply that China's influence in Southeast Asia should only be regarded from the standpoint of the challenge that it poses," Willard said.

Willard said that the US presence in the South China Sea was vital as some $5.3 trillion in trade flow through the region each year, around one-fifth of it in US commerce.

"The US military must be present there to ensure the security of those sea lines of communication and that important economic commerce for the United States and for our regional allies and partners," Willard said.