The United States is shifting more military muscle to the Pacific, including adding another aircraft carrier to the five already there.
The Pentagon's second-ranking official, Ashton Carter, has told a conference that in coming years 60% of US Navy ships will be in the Pacific, up from 52% now.
Mr Carter says the Army and Marine Corps are also working on stepped-up rotations for the Asia-Pacific region.
Last year it was announced that US marines would be based permanently in northern Australia.
Mr Carter says the US also is moving to protect fixed bases in the region. According to the Pentagon, such installations are increasingly vulnerable to Chinese ballistic missiles.
A new report presented to Congress by the US-China Economic and Security Review Commission also says Chinese cyberwarfare will pose a genuine risk to the US military in a conflict.