It's a message aimed not only at a rising China and a worrisome North Korea, but also at allies like Japan and South Korea that see a shifting security landscape at a time when US forces are bogged down in Iraq.

"While we are fighting in Iraq and Afghanistan and the global war on terror, we have no intention of neglecting Asia," Gates told reporters at US Pacific Command headquarters in Honolulu, Hawaii on Thursday.

He met there with Adm. Timothy Keating, chief of the Pacific Command, before they flew together to Singapore to attend an Asia-Pacific security conference that has become a forum for US defence officials to raise pointed questions about China's military buildup.

The Singapore visit also is an opportunity for Gates to meet separately with his counterparts from several Asian nations, including South Korea, where the decades-old alliance is facing strains. Also attending the weekend conference will be Marine Corps Gen Peter Pace, chairman of the Joint Chiefs of Staff.

Gates will address the conference on Saturday to highlight US military humanitarian efforts in Asia and the Pacific and to underscore US efforts to continue cooperation in counterterrorism campaigns. He is not expected to be as pointed in his remarks about China as his predecessor, Donald Rumsfeld, had been.

In Honolulu, Gates said the focus of his concern is not so much on details of China's military expansion but on the purposes it is meant to serve in an era in which no country is directly threatening China's own security.

"There's no question that the Chinese are building significant (military) capacity," he said. "Our concern is over their intent."