The first detachment of 200 US Marines has arrived in Australia to undertake training across the Top End for the next six months.
Eventually more than 2000 Marines will train in Australia under the program of enhanced defence co-operation outlined during the visit of United States President Barack Obama in November last year.
In a joint statement,Prime Minister Julia Gillard,Defence Minister Stephen Smith and Northern Territory Chief Minister Paul Henderson welcomed what they said was the latest chapter in the more than 60-year alliance with the US.
The initial rotation will be a US Marine Corps infantry company,which touched down in Darwin on Tuesday night.
Over the next six months,they will undertake bilateral training with members of the Australian Defence Force (ADF) as well as their own training.
Most of that will be on ADF Northern Territory training areas and ranges,including the Mount Bundey and Kangaroo Flats training areas.
It's planned that the US Marines'presence will eventually increase to a full 2500-strong Marine Air Ground Task Force (MAGTF),rotating into northern Australia in the dry season.
That comprises command,ground,aviation and logistics elements. Apart from personnel,major equipment to support the elements of the MAGTF includes wheeled vehicles,artillery pieces,light armoured vehicles and aircraft,.
Visiting US personnel will use existing defence facilities in Northern Australia for accommodation and training. Australia will provide a range of support with costs shared under existing legal,financial and logistical arrangements.
"There are no US military bases in Australia and this will not change,"the statement said.