Defence Minister Stephen Smith says big numbers of US troops and sailors could fly in and out of Perth to crew warships based at Rockingham.
Giving new details of plans for an increased US involvement in WA, Mr Smith said yesterday it was anticipated US naval vessels would have more access through HMAS Stirling naval base at Garden Island.
"We have a significant amount of potential for inter-operability here," Mr Smith said, though he would not be drawn on when it would occur.
The Government has so far given only vague details of what an increased US presence at Rockingham would mean.
"We have made as our priority, bedding down the arrangements in the Northern Territory so far as the marines are concerned and in due course, we'll move to the issue of greater access to US naval vessels, surface vessels and submarines, here (in Rockingham)," Mr Smith said.
"One of the things we have done on a one-off occasion in the past has been a crew rotation, so that possibility, into the future, does exist where the US could fly a crew into WA or Perth and essentially do a crew transfer."
Increased co-operation between Australia and the US has already led to rotations of US marines through Darwin and US aircraft having greater access to Australian airfields and bases in the NT.
Speaking after a tour of the nuclear-powered submarine USS Michigan, Mr Smith said a strong US presence in the Asia-Pacific region was needed for continuing peace and prosperity. He denied the increased co-operation between Australia and the US was a response to China's military power and influence in the region.
"We are going through a period where strategic influence in moving to our part of the world - strategic influence, political influence, economic influence," he said.
Mr Smith said America's enhanced engagement in the Asia- Pacific region was important to continued prosperity, peace and security.
Mr Smith's comments came as he said the Federal Government faced "tough decisions" about military spending in the Budget next month.
But he said military personnel, overseas operations in Afghanistan and peacekeeping missions in East Timor and the Solomon Islands were likely to be quarantined from cuts.