Perth bound? US Navy considers options for naval base.

Perth is one of four options for a US aircraft carrier group.

A proposal to expand a Perth naval base to host a US aircraft carrier was included in a US study as an example to Congress and the Pentagon how far it would be possible to increase US firepower in the region, an author of the plan says.

"We wanted to sort of help the members of Congress and the Pentagon … to think about how much we really can push your force posture," said Michael Green, an Asia specialist at the US Centre for Strategic and International Studies, which was commissioned by the US Department of Defence to write a report on refocusing America's military might on the Asia-Pacific region.

"We looked at it and we thought: 'That would be a lot of firepower.'

"And so if we think of it only in those terms, why not?" said Dr Green, speaking after testifying about the report to a congressional committee.

The CSIS report included the proposal as part of one of four options the US military could use as a framework to "pivot" its focus towards the region as part of the strategy announced by President Barack Obama last year.

"Australia, Perth, the Cocos Islands are not only strategically positioned as a Pacific location but also as an Indian Ocean location and, as that southern arc becomes more important in maintaining overall stability, Australia's role is going to be more important," Dr Green said.

"But when you look at the economic feasibility, when you like at the capacity of Australia as host nation to support this … it is a massive investment," he said.

He said the cost and the capacity of Australia to absorb such a large force could make it unfeasible.

The Australian Defence Minister, Stephen Smith, said in a speech in Canberra last night that Australia would look at an increased US presence at HMAS Stirling.

"For Australia, this presence will support our long-held strategic interests in maintaining and expanding US engagement in our region."

A spokeswoman for the US Department of Defence, Major Catherine Wilkinson, said earlier today US time that the US was focused on its Marine and Air Force co-operation in Darwin at present.

"Further opportunities may emerge over the longer term for co-operation, but for right now we're paying attention to getting the first two correct," she said.

"We will continue discussing ways to increase our co-operation and interoperability with our Australian allies. No decisions have been, or will be, made without the full concurrence of both countries."

The report noted that the alliance between Australia and the United States enjoyed bipartisan political and significant public support, and that the location was strategically suitable as America prepared its military to meet the rise of China.

Dr Green said the increasing co-operation between the US and Australian military in Darwin was more feasible.

"The deployment of Marines [to Darwin] makes a lot of sense, the US Air Force and the Australian Air Force sharing facilities, working together makes a lot of sense.

"From the Australian side, I think the real advantage in having the Marines and everything they bring in Darwin, is what a great opportunity for the Australian Army and Royal Australian Air Force and Navy to develop joint amphibious ready deployment capabilities and work together."

He also said he believed Australia should work with Japan and the United States to replace the Collins-class submarine fleet, noting that the US had worked on weapons systems for Japanese long-range attack submarines.

Dr Green told the committee that the US's new force posture in the region should support a strategy to deter any nation from challenging the US or its allies in the region, partly by demonstrating its own willingness to maintain its forces in the region, but also by integrating them with allies.

"You can't do this from the continental US; you have to have forward posture," he said.

The committee heard that the Pentagon was not considering building a base in Australia, but was in talks about expanding shared infrastructure, particularly in Darwin.

"We are looking to use shared facilities … that is how we are approaching this discussion but as yet we do not know the full extent of the infrastructure needed or required for our presence and what Australia has to offer and what we are looking to do," US Deputy Assistant Secretary of Defence for Plans Robert Scher told the committee.