The USFPI are an extension of Australia’s existing Defence relationship with the US and support the common interest of promoting regional security and stability.

The MRF-D has grown in size and complexity since the first rotation of US Marines through Darwin in 2012. In 2019, the goal of 2500 US Marines training with the ADF stationed in Darwin was reached.

The structure of MRF-D continues to evolve in response to the changing environment and advances in technology, with the focus shifting to capability rather than numbers. Highly complex joint training scenarios are now being executed, which continue to challenge our forces and better prepare us to rapidly respond in the region, if and when called upon to do so.

This year, about 2200 US Marines and sailors conducted a comprehensive range of training activities, including humanitarian assistance, security operations and high-end, live-fire exercises – exercises that develop enhanced interoperability between the ADF and US Marines and key partners.

At AUSMIN in September 2021, Australia and the USA announced the agreement to enhance force posture cooperation in four key areas to: establish an integrated logistics capability, expand existing enhanced air cooperation, enhance maritime sustainment cooperation, evolve bilateral and multilateral operations and exercises.

The US military plans a dramatic and comprehensive ramping-up of its defence presence in the Northern Territory to counter the rising threat of China – measures which experts say will, for the first time, involve all four branches of the American armed services.

Senior US and Australian defence officials and analysts, speaking on background, confirmed to the Defence Special Report that while “final details were getting worked out”, the measures envisaged big increases in joint US air exercises, troop deployments, pre positioning of equipment, and the use of more sophisticated weapons systems across the Northern Territory’s key training ranges.

Spurred by growing perceptions of a rising Chinese threat, last month’s announcement of the AUKUS trilateral defence agreement will see the transformation of the Top End from a very convenient military training area for the ADF and its allies to a vital southern US defence anchor encompassing a vast area of the Pacific, linking Guam to the north and Hawaii to the east.

These are bigger consequences and will have a bigger, more immediate, impact to the region.

The AUKUS announcement has fuelled more speculation about possible expansion of the marines' presence in the Top End, which Defence Minister Peter Dutton has already said he would like to see.

In an interview with the ABC, the USA's Charges d'Affaires in Australia, Michael Goldman, said talks on the subject were ongoing.

Michael Shoebridge, the director of defence, strategy and national security at the Australian Strategic Policy Institute, said northern Australia was becoming another staging point for US personnel, logistics and resources in the Asia Pacific.

Under the 2011 agreement, marines will keep returning to Darwin each dry season for 25 years, ending in 2036. The USA Charges d'Affaires, said the deployments were "just a beginning rather than an end" of the US presence in Australia.

A former Australian assistant defense secretary says there might be more Marines in Australia in the wake of a new trilateral defense alliance.

AUKUS, which officials had been talking about for the past 18 months, is about much more than submarines, Babbage said.

“We are going to see larger U.S. forces coming, including U.S. Army forces and air power coming here on rotation,” he said. “It’s quite likely the Marine Corps presence could be scaled up.”

The U.S. Embassy in Canberra and the Australian Defence Department did not respond Friday to questions about the possible effect of the trilateral defense pact on the Marine rotations.

About 2,200 US Marines expected in Darwin in the 2021 rotation as Canberra also eyes improved air, maritime capability.

Outlining further measures on a visit to Washington, Defence Minister Peter Dutton said on Thursday that 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 10-year rotation through the northern city of Darwin.

“I do have an aspiration to make sure that we can increase the numbers of troops through the rotations,” Dutton said.