The first batch of 2,500 US Marines to be deployed in Australia began work Wednesday as Washington bolsters its presence in the strategically vital Asia-Pacific, to the irritation of China.

Some 200 Marines touched down in tropical Darwin overnight as part of an enhanced defence cooperation outlined during a visit by US President Barack Obama in November that rankled Beijing.

The troops are in the Northern Territory on a six-month rotational basis and will be based at Robertson Barracks on the outskirts of the city, building to some 2,500 by 2016-17.

In a joint statement, Prime Minister Julia Gillard, Defence Minister Stephen Smith and Northern Territory Chief Minister Paul Henderson welcomed what they said was the latest chapter in a more than 60-year alliance with the US.

"It represents an evolution of existing exercises and activities that the United States already conducts with the Australian Defence Force in Australia," they said.

"The intent in the coming years is to establish a rotational presence of up to a 2,500 personnel Marine Air Ground Task Force, rotating into Northern Australia in the northern dry season.

"There are no (permanent) US military bases in Australia, and this will not change," they added.

The US military currently has only a limited deployment in long-standing ally Australia, including the Pine Gap Joint Defence Facility spy station near Alice Springs.

The latest move represents a significant geo-strategic shift by Washington and it has irked Beijing, whose rapid rise is reorienting Asia's balance. China has said the Marines deployment is proof of a "Cold War mentality".

Wang Jisi, the influential dean of the School of International Studies at Peking University, writes in a candid new study that a mistrustful China is convinced that the United States is bent on holding back its rise.

But the deployment has reassured some Asian countries who see it as a statement that the United States intends to stand up for its allies and interests in the region.

And while it appears to be sending a signal to China and its expanding military, the White House has also made clear it wants to extend its capability to deploy for disaster relief missions in Southeast Asia.

US Ambassador to Australia Jeffrey Bleich said Washington wanted to make sure the region remained peaceful and stable.

"The way we accomplish that is by ensuring that trade routes are open and that we are prepared for any issue that could come up," he told reporters.

"The opportunity to train in Darwin is ideal for having the ability to do that. You have access to the Pacific Ocean, to the Indian Ocean, to the East Timor Sea and the trade routes all around."

Defence Minister Smith also sought to reassure regional nations, suggesting that Australia's closest neighbour Indonesia and even China, Canberra's most important trading partner, could be included in future joint exercises.

"Indonesian President Susilo Bambang Yudhoyono, he came out saying he thought it was a good thing," Smith told ABC radio of the US deployment.

"And he also said that he saw the prospect of not just Australia, the United States and potentially Indonesia engaging in exercises but also the wider region including China," he said, welcoming such a development.

As part of the major expansion of military ties, Australia last week said it may allow the United States to use its territory to operate long-range spy drones.

Washington could also reportedly station US aircraft carriers and nuclear-powered attack submarines in the western Australian city of Perth.