A former top intelligence adviser to President Barack Obama predicts Australia could play a "very consequential" role if a war breaks out between the United States and China.

David C Gompert was principal deputy director of National Intelligence from 2009 to 2010 and has just led a US Army-commissioned report examining the prospect of the two military powers going to war.

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The report War with China: Thinking Through the Unthinkable says war between the US and China would be long, destructive and could erupt if regional disputes already underway overheat.

The 115-page document by the Washington-based RAND Corporation also suggests Australia, as a close American ally, could play a pivotal role if tensions with Beijing escalate.

"Depending on the cause and focus of the conflict, other East Asian states would mostly side with the United States in varying degrees: from support ranging from permission to use bases to the possible commitment of forces (eg Australia, New Zealand, the Philippines)," it says.

"The participation of Australian forces, because of their quality, could have military significance despite their small size.

"Apart from military contributions, the longer and more severe the conflict, the more and perhaps more permanently China could become isolated from the very region it aspires to lead."

Australian involvement would take many forms

Mr Gompert said as a long-standing American ally, Australia could play a pivotal role in any eventual war with China.

"Australians would know better than I what Australia might do, but I would say that [what] Australia would do could be very consequential," he told ABC Radio's The World Today.

David C Gompert says US and Australian forces know how to work together – an advantage in a war. ( US National Intelligence )

The former intelligence chief said an Australian contribution could take several different forms.

"For Australia to support the United States in logistical ways, for Australian forces to take on missions that American forces had been fulfilling, freeing up for the conflict," he said.

"For Australian forces to actually enter operations, and of course American and Australian forces do know how to operate together — that would produce significant operational consequences for the Chinese."

Last week satellite photos emerged revealing Beijing has begun constructing reinforced hangars designed to house combat jets on several artificial South China Sea outposts.

On Saturday the South China Morning Post cited a Chinese administration source saying the country could begin construction work on the disputed Scarborough Shoal before the US Presidential election in November.