US Defence Secretary Chuck Hagel has accused Beijing of involvement in cyber espionage in a speech at a security forum attended by Chinese military officials.
Speaking at a security conference in Singapore on Saturday, Hagel openly blamed the Chinese government and military for "cyber intrusions" into sensitive US information systems.
The accusation comes ahead of a summit between the leaders of the two countries next week.
"The United States has expressed our concerns about the growing threat of cyber intrusions, some of which appear to be tied to the Chinese government and military." Hagel said.
The US, he said, is determined to work closely with China and other nations to establish appropriate standards for behavior in cyberspace.
Noting America's longstanding tensions with China, Hagel said: "The key is for these differences to be addressed on the basis of a continuous and respectful dialogue."
The two nations, he said, must build trust in order to avoid military miscalculations.
Hagel also told Asian nations that despite sharp budget cuts, the Pentagon will continue to shift its military troops, ships and aircraft to the Pacific region
The Asia-Pacific, said Hagel, was at the epicentre of historic changes around the world, pointing out that the US was committed to strengthening its military, economic and diplomatic partnerships with nations across the region.
As part of that he noted that the US would set aside $100 million to expand its military exercises in the region.