US Defence Secretary Robert Gates has said the US wants a larger military presence in Asia.
On his way to Australia for annual security talks, Mr Gates said closer ties with Australia would help the US expand its role in South East Asia.
The US would focus on fighting piracy, improving counter-terrorism, disaster aid and cyber-security, he said.
He said the US move was not to contain China, which is engaged in various territorial disputes in the region.
Mr Gates said Washington had no plans for more bases in the region.
But he expressed hopes for increased co-operation on issues such as missile defence and "space surveillance".
"We're looking at a number of different options," he said.
Concerns have intensified around the region since China published maps earlier this year claiming the entire South China Sea as part of its territory.
But Mr Gates said: "This isn't about China at all."
"It is more about our relationships with the rest of Asia than it is about China," he told reporters travelling with him.
A senior US defence official told reporters that the Pentagon is "looking at how we can make sure our forces are not just oriented in north-east Asia, but are looking down to south-east Asia and then into the Indian Ocean as this part of the security environment becomes more important".
'Force for good'
Australian Prime Minister Julia Gillard said everyone hoped China could play a larger role in regional co-operation.
"I think we will be talking about the geopolitics of our region, and that means of course we'll be talking about the rise of China and as China rises, what sort of force it is going to be in the world," she said.
"I believe we have a shared perspective with the United States that we want China to be a force for good, strongly engaged in global and regional architecture, strongly engaged in a rules-based framework."
She spoke of the benefits for Australia of closer military ties with the US.
US Secretary of State Hillary Clinton is also visiting Australia.
"We have made the point to China, both privately and publicly, that there does need to be transparency about China's military strategy," said Australian Defence Minister Stephen Smith.
"Australia believes that China will emerge... to use the Chinese phrase, into a harmonious environment. It will be a responsible international stakeholder. And that's what we want to see," he added.
Australian Foreign Minister Kevin Rudd said Australia would "welcome the United States making greater use of our ports and our training facilities, our test-firing ranges. That has been the case in decades past and will be the case for decades in the future".
There is controversy in Australia on the idea of sharing bases, which could mean more US soldiers present in the country.