The Australian government has cancelled a number of defence projects – including a “roll-on, roll-off wharf” in Darwin and new air-to-air refuellers – as it sharpens the military’s focus on deterring threats in an increasingly uncertain Indo-Pacific region.

The force structure plan reveals the government is dumping several proposals that were included in the 2016 white paper but “are no longer required”.

These include a roll-on, roll-off wharf in Darwin to load heavy vehicles and cargo on to Australia’s two Canberra-class amphibious ships.

It has also scrapped the “northern advanced joint training area” – a proposal for a site for large-scale, joint and combined amphibious training exercises and a potential rail link to RAAF Base Tindal, near Katherine in the Northern Territory, to transport explosive ordnance and bulk fuel.

But the government says it will still meet a pledge to invest $8bn in northern Australia over 10 years.

This year’s deployment to Darwin, in Australia’s Northern Territory, hasn’t gone as initially planned. Travel restrictions and quarantining requirements due to the novel coronavirus drove the Marine Corps to send a smaller, 1,200-member force for the rotational deployment program, now in its ninth year. That’s less than half the size that deployed in 2019, the first time Marine Rotational Force-Darwin reached its 2,500-personnel maximum.

The deployment will culminate in exercise Koolendong in September with Australian Defence Force units.

The Marines will be in quarantine for two weeks, where they also will be tested twice for the potentially deadly COVID-19 virus.

Just before the newest wave of Marines showed up to Australia, Marines in the first wave of “approximately 200″ Marines were released from the quarantine facility, according to Chuck Little, deputy director of communication strategy and operations for U.S. Marine Corps Forces, Pacific. All Marines in the first wave tested clean from the virus, according to the Marine Corps.

“At the end of the day all it did was delay the deployment a little bit and force us to take a little harder look at how we were going to implement the necessary health protective measures,”

This year’s rotation, delayed by two months due to the coronavirus pandemic, includes 1,200 Marines, fewer than half as many as headed south last year.

Last year, the force brought with it 10 MV-22 Osprey tiltrotors, four AH-1Z Vipers and three UH-1Y Venom helicopters, but the coronavirus meant there aren’t any manned aircraft heading south this time.

The Marines won’t be going to sea on Australia’s amphibious ships HMAS Canberra and HMAS Adelaide, as they did last year, he said.

“It’s the first time for the rotational force to incorporate unmanned aircraft,”

The modified rotation of US Marines will carry out exercises exclusively at Australian Defence Force training areas in the Northern Territory after undergoing two weeks' quarantine at a Defence base in Darwin.

Defence Minister Linda Reynolds gave approval US Secretary of Defense Mark Esper for the reduced contingent in May.

At the time, she said the approval "was based on Australia's record to date in managing the impacts from COVID-19, as well as strict adherence by deployed US Marines to the mandatory 14-day quarantine and other requirements".

Despite the arrival of US Marines, Australian borders remain closed.

The last confirmed cases of coronavirus attributed to the Northern Territory came on May 1, when two Australian Defence Force personnel, who contracted coronavirus on deployment in the Middle East, were flown to Darwin.