The CSIS was directed to consider how the US military could undertake the "pivot" to the Asia-Pacific region announced by President Barack Obama last year in response to China's increasing influence. The third option in the report - formally titled US Force Posture Strategy in the Asia Pacific Region: An Independent Assessment - details moving a US carrier strike group to the HMAS Stirling base in Perth. The strike group would include a nuclear powered aircraft carrier, a carrier air wing of up to nine squadrons, one or two guided missile cruisers, two or three guided missile destroyers, one or two nuclear powered submarines and a supply ship. "Australia's geography, political stability, and existing defence capabilities and infrastructure offer strategic depth and other significant military advantages to the United States in light of the growing range of Chinese weapons systems, US efforts to achieve a more distributed force posture, and the increasing strategic importance of south-east Asia and the Indian Ocean," says the report. "Enhanced US Navy access to Her Majesty's Australian Ship Stirling (submarines and surface vessels) is a possible next phase of enhanced access arrangements with Australia," it says.

"HMAS Stirling offers advantages including direct blue-water access to the Indian Ocean and to the extensive offshore West Australian Exercise Area and Underwater Tracking Range, submarine facilities including a heavyweight torpedo maintenance centre and the only submarine escape training facility in the southern hemisphere, and space for expanded surface ship facilities, including potentially a dock capable of supporting aircraft carriers." The report suggests the US could also consider building airport facilities to support "bombers and other aircraft". It suggests other initiatives could include "increased US support for Australia's ailing Collins class submarine replacement project" and "full Australian participation in US theatre missile defence". The other options consider how the US military could direct its "force posture" to the region with different levels of military power. Comparable cost estimates in the past have ranged from $1 billion to create a nuclear-capable homeport for a carrier at Mayport in Florida to $6.5 billion for similar capability in Guam

Option one lays out a plan for using existing forces where they are now stationed. Option two describes how the military could operate given the increases already planned for. Option three, which includes the build-up in Australia, presumes an increased force, and option four lays out plans for a decreased force. The Defence Secretary, Leon Panetta, has already stated he plans to increase the US naval presence in the region from 50 to 60 per cent of the total force. The report says such a fleet in Perth would be a "force multiplier" and estimated it would provide the equivalent military benefit of having three similar groups based outside the region. "HMAS Stirling is not nuclear carrier-capable," the report says. "This forward-basing option would require significant construction costs. Comparable cost estimates in the past have ranged from $1 billion to create a nuclear-capable homeport for a carrier at Mayport in Florida to $6.5 billion for similar capability in Guam." Option three also proposes basing intelligence, surveillance and reconnaissance drones and aircraft in either Australia or Guam.

According to the report the carrier base would "present some operational constraints" because of Perth's southern location, "further from trouble spots in the Western Pacific than Guam, and further from the Middle East than Diego Garcia". But it says the distant location could also be a benefit by putting it beyond the increasing range of China's defences. It said the option was "subject to important variables" including how well the new US Marine presence in Darwin was welcomed by the local community and whether bipartisan support for the increasing military ties between Australia and the US could be maintained. The study notes that Australia's strategic history "is one of a close alignment with a 'great and powerful friend'". It says public support for the US alliance is at an eight-year high, with "87 per cent of Australians regarding it as important for Australia's security and 74 per cent considering the United States as Australia's most important security partner over the next 10 years.

"While not mainstream, anti-Americanism is prevalent among some elite circles, particularly in academia, parts of the media, and the fringes of the trade union movement and politics," it says. "Australia is unique among America's allies in having fought alongside the United States in every major conflict since the start of the 20th century," the report notes. A spokesman for the CSIS said the think tank was unable to comment on the report until after some of the report's authors testified before the Senate Committee on Armed Services tomorrow, Wednesday US time. The paper criticised the US Department of Defence for failing adequately to articulate the new Asia Pacific strategy, nor detailing how it would manage the change in the face of budget constraints. In a statement the Armed Services Committee's chairman, Senator Carl Levin, said he agreed with comments made by the US Secretary of Defence, Leon Panetta, that "efforts to strengthen alliances and partnerships in the Asia-Pacific to advance a common security vision for the future is essential to the US strategy to rebalance toward the region".

In a cover letter to the report written by the CSIS president John Hamre to Mr Panetta, Mr Hamre writes: "We found a strong consensus on this overall objective within the Department, in the policy community generally, and especially with allies and partner countries." The proposal met a lukewarm reaction in Western Australia with the Premier, Colin Barnett, saying it would never happen. Loading "I don't think there's any possibility of that happening," he said. "I don't think you could squeeze a nuclear aircraft carrier into Cockburn Sound." - with Courtney Trenwith