Australia's new strategic alliance with the United States and United Kingdom is likely to see more troops, war planes and naval vessels in the Top End. But any expansion could be hindered by the controversial lease of Darwin Port to a Chinese company, national security experts say.

Heralded as the most significant shift in Australia's defence direction in decades, the centrepiece of the trilateral security partnership, dubbed "AUKUS", is a plan to build a fleet of nuclear-powered submarines.

But Defence Minister Peter Dutton has also flagged a major enhancement in Australia's military cooperation with the US, which currently deploys about 2,500 marines to the Top End each dry season.

John Coyne from the Australian Strategic Policy Institute said the 99-year lease of the Darwin Port to Landbridge could prove an impediment to the allies' military expansion plans.

WASHINGTON: Australia said Thursday that more US troops will rotate through the island nation and that the allies will cooperate on missiles, the latest joint steps amid shared concerns over a rising China.

Outlining further measures on a visit to Washington, Defense Minister Peter Dutton said Australia will be “significantly enhancing” cooperation including working together on the development of missiles and explosive ordnance.

He said Australia was willing to see more US Marines in a decade-old rotation through the northern city of Darwin

US Defense Secretary Lloyd Austin, also without giving numbers, confirmed that the United States “will expand our access and presence in Australia.”

Australia is open to boosting American troop rotations and increasing military plane visits as defence co-operation between the allies ramps up.

A historic pact to share nuclear-powered submarine technology - under the umbrella of a new alliance known as AUKUS - has been signed as Australian ministers held talks with counterparts in the United States.

Foreign Minister Marise Payne and Defence Minister Peter Dutton met with US Secretary of State Antony Blinken and Defense Secretary Lloyd Austin on Friday morning for the latest AUSMIN talks.

Mr Dutton said he aspired to increase troop rotations and other military co-operation between the two nations.

"If that includes basing and includes the storage of different ordinances, I think that is in Australia's best interests, in our national interests at this point in time."

After an SBS News investigation revealed women’s claims made against US marines stationed in the Northern Territory were shifted overseas or dropped, there are calls for the Senate to look into the issue and for a legal agreement covering US military personnel in Australia to be revised.

Senator Rex Patrick said the cases were “awful” and encouraged women to come forward.

Professor Donald Rothwell, an expert on international law at the Australian National University, said the 1963 SOFA should be revised and brought up to modern standards in light of SBS News’ revelations.

“It’s time this SOFA was looked at to see whether it’s robust enough to protect Australian citizens.”

Women Veterans Network Australia spokeswoman and former Australian Army major Dr Kerry Summerscales said calls for a revision of Australia's SOFA with the US was "urgently overdue".

EXCLUSIVE: Documents obtained by SBS News have revealed several allegations of sexual assault made against US marines serving in Australia, with investigations into them being shifted overseas or dropped. Some survivors also say they felt discouraged by the Australian Defence Force from following through on their complaints.

One woman woke to find a US marine assaulting her in her bed, another was taken to hospital after having her drink spiked at a military barracks, and a third believed a US marine grabbed her and tried to sexually assault her at a bar. All the incidents took place in Australia’s Northern Territory, but the investigations into them were either handed over to US authorities, stalled, or dropped.

SBS News has obtained a series of reports between 2015 and 2021 from the Australian Defence Force Investigative Service (ADFIS) under freedom of information laws. They detail six alleged assaults or indecent acts involving US military personnel whilst on rotation in Australia, including members of the Marine Rotational Force - Darwin, a contingent of up to 2,200 personnel regularly based in the Northern Territory since 2011.

FFS - The case was passed on to NT Police, which took charge of the investigation, to consider whether it warranted a criminal investigation “due to jurisdictional concerns”.