Thousands of US Marines have arrived on our shores for a mission that is also bolstering the amphibious warfighting capability of the Australian Army.

The Marines – who arrived in the Northern Territory for their 12th annual rotation in March – specialise in amphibious operations and are also in the middle of a major transformation to match China’s armed forces.

Colonel Brendan Sullivan, the commanding officer of this year’s Marine rotational force, said this year’s training exercises in Australia and the surrounding region offered “incredible opportunities”.

Asked if they were seeking to replicate potential conflict scenarios in the South China Sea, the Pacific Islands or the Taiwan Strait, Colonel Sullivan said that was something “we’re grappling with right now” as the Marines sought to project force across a greater range.

“We’re going through a force design process where we’re trying to achieve the force that we think we’re going to need to have in the years ahead … and trying to get after some of the challenges that we think are associated in those operating environments,” he said.

“We’re trying to posture so that we can be ready to operate in that type of environment in the near future.”

This year’s Marine exercises include Predator’s Run in the Northern Territory and Melville Island, north of Darwin.

Ten Marine Corps MV-22B Ospreys have arrived in Australia’s Northern Territory as part of a 2,500-strong rotational force, the Marine Corps said Tuesday.

The Ospreys, from Marine Corps Base Hawaii’s Marine Medium Tiltrotor Squadron 363, are deployed to Royal Australian Air Force Base Darwin, according to a Marine Corps statement and information released Friday by the U.S. Department of Defense with photographs of the aircraft.

The tiltrotors, air crew and support personnel make up the air combat element of Marine Rotational Force — Darwin, which began its annual seven-month rotation last month.

The 12th contingent of the rotational force since 2012 will practice expeditionary operations, geographically distributed communications, non-combatant evacuation, embassy reinforcement, humanitarian assistance/disaster relief and rapid projection of combat power

The Albanese government will dedicate $2 billion to the Learmonth, Scherger and Townsville air bases, a facility in the Cocos Islands and bases in the Northern Territory.

Australia began bolstering its northern defences in 2011 when then-prime minster Julia Gillard and then-United States president Barack Obama agreed to US Marines and aircraft being permanently rotated through Darwin.

This week’s review, which signalled a need to start projecting force into the region, recommended an urgent and comprehensive remediation of northern bases to better enable the Australian Defence Force to operate from them.

The $19 billion to be spent over the four-year forward estimates period will be fully offset by savings elsewhere in the defence portfolio. Beyond that, however, defence spending, currently about 2 per cent of GDP, will begin to grow as the true cost of the AUKUS submarines and long-range missile programs begin to bite.

The Northern Territory is poised to play a key role in Australia's future missile defences, according to a Top End MP, as the region prepares for an influx of soldiers and defence force spending.

The presence of the US Marines in Australia's Top End is also poised to grow in the years ahead, with the review recommending an increase to the annual rotation.

The report called for greater "engagement with the US on deterrence, including through joint exercises and patrols; and strengthening Australia's sovereign military and industrial capabilities".

Dr Coyne said this could play out through the arrival in the north of more US ships and fighter jets annually.

"There's a strong possibility that we'll see more often, more frequent US Navy ship visits," he said.

"Certainly we're most likely to see a greater rotational force of US air force craft through northern Australia."

Federal government MP Luke Gosling said the country's north would be prepared to play its part. "There's no doubt that the Northern Territory and the Top End will be part of the [nation's] missile story," he said. "Why? Because we're defending Australia, and obviously, you can get more range into the northern approaches to Australia from the Top End."

The national significance of key Northern Territory infrastructure assets has been singled-out in a crucial new defence review released on Monday.

The Defence Strategic Review found recent severe flooding which closed the Stuart Highway and Alice Springs to Darwin railway this year had “highlighted the importance” of well-maintained resilient civil infrastructure, including ports and roads that support the network.

The future role of Robertson Barracks, home to the 1st Brigade, in our ongoing defence is unclear, but could potentially be beefed up.

The report forecasts “significant changes to army force posture and structure”, saying army combat brigades “may be re-roled and select capabilities postured in Northern Australia”.

One of six key recommendations is to improve the Australian Defence Force’s capacity to operate from Australia’s northern bases.