The defence minister, Richard Marles, has refused to say when American B-52 aircraft will start operating from the Northern Territory.

Asked a direct question about whether he knew when B-52 aircraft would start their deployments from the RAAF base in Tindal, 320km south-east of Darwin, he replied:

Look, I’m not about to go into those details. Again, we are working very closely with our American partners.

There is a significant force posture initiative that’s being undertaken between ourselves and the United States, which I might say is seeing enormous American investment in our northern bases here at Darwin and Tindal, but across the north, that [provides] a huge advantage for our country.

The B-52 is a long-range, heavy bomber that can carry out ocean surveillance and anti-ship operations and “can carry nuclear or precision guided conventional ordnance”

Northern Australia’s national security has received a significant boost with the completion of upgrades to Nackeroo Airstrip at Bradshaw Field training area south of Darwin.

Part of the Commonwealth’s $747m NT Training Areas and Ranges Project, the Nackeroo Airstrip works included sealing the infrastructure to increase its capacity to take heavy aircraft.

Defence said the enhancements would allow military designated aircraft like the C-17A Globemaster and MV-22 Osprey to land at Bradshaw for the first time.

Territory company Sitzler has the contract for the ranges project upgrades, supported by a number of Territory contractors including RPS Group.

“The upgrade significantly enhances the ability to undertake air, land and littoral operations from here which will lead to increased training outcomes and collective training with the United States, ADF and other partner countries.

The US military could be waiting until next year for the handover of 11 fuel storage tanks currently under construction at Darwin’s East Arm.

Originally scheduled for completion last September, the opening was put back until this July but with just weeks to go, construction flaws and permitting issues continue to dog the $270m development.

The liners beneath the tanks are leaking, environmental permits remain in limbo and building certifications are unresolved.

A spokesperson for the Department of Infrastructure, Planning and Logistics, which has carriage over certification, said under the Act, a building permit was required before work starts, and work must be certified or approved at the end of construction before occupancy.

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.