American warships could be stationed permanently in Darwin as part of the United States military's strategic plan in the region, but an expert warns that will not sit well with China.

US chief of navy operations, Admiral Jonathan Greenert, said the US was considering having a permanent naval base in Australia.

Admiral Greenert recently visited Darwin to inspect facilities and infrastructure which could allow US warships to be based in the Top End.

At an address in Canberra this week Admiral Greenert said the US was "doing a study together with the Australian Defence Force to see what might be feasible for naval co-operation in and around Australia, which might include basing ships".

Australian National University (ANU) Senior Fellow Peter Dean said such a move would be part of the US plan for Asia and would add to the existing US Marine Corps presence in Darwin.

"That started off small up there in Darwin as part of the US rebalance in the region. And that's slowly increasing the number of US marines based up there in Darwin," Dr Dean said.

"The plan that Admiral Greenert put out for that marine rotational force was to grow it to what he called a marines expeditionary unit.

"That is an all-arms combined force."

China won't like it: expert

Dr Dean said any such move would be sure to ruffle some feathers with China.

"They don't particularly like having a forward US presence in the region," Dr Dean said.

The naval base would be used to refuel and repair ships - and for sailors to have some down-time.

Up to 2,500 US marines will be stationed in Darwin by 2017 under an agreement reached between former prime minister Julia Gillard and US president Barack Obama.

A US Navy carrier is met by pilot boats to bring it into Darwin Harbour in 2010. ( ABC News )

Dr Dean said the US troops would be good for Darwin's economy and for their Australian counterparts.

"It also provides some really good training opportunities for the Australian Defence Force," he said.

In August last year, about 1,500 US marines and Australian soldiers trained in hot and dusty conditions at a former cattle station 600 kilometres south of Darwin.

Chinese troops have trained with Australian and US forces in the NT as recently as 2014.

Indonesia has also expressed concern at US military escalation in the Top End.

Dr Dean said the warships could be based in Darwin within a few years, but the US was still investigating infrastructure requirements.

In December last year, the ADF unveiled its new $125 million joint logistics facility in Darwin, which is expected to be used to support US marines rotating through the Top End.

"My understanding is those who are in charge today see this as a potential site for doing some of that support for the marines," retired Major General Peter Haddad said.