Darwin's local economy will benefit by about $5 million when the number of US Marines based there swells to more than 1100 next year.
The most recent rotation of 200 Marines returned to Hawaii in late September but locals will profit when numbers rise to 1150 during the next dry season, according to Defence Air-Vice Marshal Neil Hart, Head of the Joint Capability Co-ordination Division.
"We're expecting an increase in the Darwin economy from about $1.3 million with this last rotation (of Marines) to about $5.5 million, on top of fuel, logistics, and all those other things that will flow through from their activities," he told the Northern Australia Defence Summit in Darwin on Tuesday.
Defence this month began working on upgrades for additional working and living accommodation at Robertson Barracks and RAAF Darwin, which will also be used by the Marines, he said.
"The upgrade will cost about $11 million and we're working out how to share and recover costs with the US," Air-Vice Marshal Hart said.
"With 1100 Marines here for up to six months a rotation, there's likely to be increased access or requests for use for personal recreational and other facilities, on top of increases to logistics and service support," he said.
He stressed that extra demand would have a minimal negative impact on the community.
"What Defence is looking to do, to make sure that doesn't distort our arrangements, is that most of that demand will be channelled through existing defence contracts," he explained.
He pointed out that the Marines who come to Darwin are very experienced, toward the end of their training and mostly self-sufficient.
"These guys are Marines by their very nature, ready to fight, so there's not a lot of equipment and things they'll need from the local community," Air-Vice Marshal Hart said.
The Northern Territory has a large Defence Force population, with about 15,000 Army, Navy and Air Force personnel - and their families - residing in the area.
They represent about 10 per cent of the ADF.About $1 billion is spent on Defence in the NT each year, or about 6 per cent of its total expenditure.