Two hundred US Marines arrive in Darwin on Sunday for the second six-month rotation of US troops training in Australia's north.

Defence Minister Stephen Smith said the troops would stay at Darwin's Robertson Barracks and train alongside troops from Australia and other nations in the region.

The US troops would also train on their own at defence facilities in the Northern Territory.

The rotation is part of the enhanced Australia-US Defence cooperation announced by Prime Minister Julia Gillard and United States President Barack Obama in November 2011.

Mr Smith said the plan was to have rotations of up to 2500 Marines in Northern Australia in the northern dry season by 2016-17, but the government had not yet made any decisions about arrangements for larger US Marine Corps rotations.

He said a social and economic assessment of last year's rotation found social impacts of the US troop visit were minimal or negligible, but there would be a small positive economic benefit.

As the next step, an assessment was now being undertaken of impacts of deployments of up to 1100 US Marines to northern Australia, Mr Smith said in a statement.