The US Defence Department is seeking businesses for extensive upgrades to RAAF Base Darwin.

The works are part of the US Force Posture initiative to enhance security in the Asia-Pacific region - including construction of a parking apron, a maintenance support facility and an aircraft maintenance hangar at RAAF Base Darwin.

The contract also includes an aircraft rinse facility, aircraft wash rack, helicopter landing pads and supporting facilities as well as construction of Marine aviation logistics squadron and Marine wing support squadron facilities - as well as a Type 11 aircraft maintenance hangar, telecommunications distribution facility, supporting facilities, utility connections, site improvements and earthworks.

Under the Force Posture, Australian businesses and joint ventures have won United States-funded infrastructure contracts to the value of almost US$200m.

This includes the completion of a new fuel facility at RAAF Base Darwin to support enhanced air co-operation between the United States and Australia and construction of a US tank storage facility at East Arm, which is behind schedule but expected to be completed by July.

In addition, tens-of-millions was spent upgrading RAAF Base Tindal in Katherine to support KC-30A multi role tanker transport operations, which Defence said will enhance air mobility, including air-to-air refuelling and air logistics support missions.

Tens-of-millions more have been spent developing the MQ-4C Triton drone, four of which will be deployed at RAAF Base Tindal near Katherine from later this year.

The American military has taken over an investigation into the death of three Marines during a training exercise on a remote island off the Northern Territory.

NT Police were leading the response after a horror military aircraft crash on the Tiwi Islands on Sunday August 27.

There were 23 troops on board the tilt-rotor military aircraft when it went down, with the two pilots and crew chief understood to have sacrificed their lives to avert a catastrophic crash killing all on-board.

Under the Commonwealth Defence Visiting Forces Act, the Territory coroner was barred from holding an inquest into the three marines’ deaths with the initial reports passed onto the American authorities.

About 100 metres from the end of a runway earmarked to take spy planes for the Australian Defence Force and its allies, hundreds of vulnerable turtles are starving and dying.

The Australian government has reneged on its 1984 commitment to the UN “that it had no intention of making the Cocos (Keeling) Islands into a strategic military base or of using the Territory for that purpose” - part of the agreement to the Act of Self Determination for Cocos to be integrated into Australia.

Three American marines have been killed in a horror crash during a military exercise off the coast of the Northern Territory.

The Marine Rotational Force Darwin confirmed three of their personnel had died, while another five were flown to Royal Darwin Hospital in serious condition following an Osprey crash over the Tiwi Islands at 9.43am, Sunday.

He said the aircraft, with 23 personnel on board went down while transporting troops during a routine training exercise, known as Predators Run, near Pickataramoor, Melville Island, 80km north of Darwin.

“Recovery efforts are ongoing,” a MRF spokesman said.

The cause of the incident is under investigation.

A new US Air Force will build a "mission planning" and operations centre in Darwin, as part of $630 million in American spending across the top end over the next two to three years.

The "Squadron Operations Facility" in Darwin will add to its growing array of military assets in the north, raising fears Australia may be locked into any future military conflict between China and the USA.

The tender documents say the Squadron Operations facility in Darwin will be used for maintenance, mission planning, intelligence and crew briefings — it is budgeted to cost $US26 million ($40 million).

“Being able to organise and deploy forces outside of the dense missile attacks that China is likely to use against places like Guam and Okinawa is part of the strategic logic,”