USA war planes including the eight-engine bombers and fast fighter jets will operate from RAAF Base Darwin and Tindal. The NT is set to be pounded by the world’s oldest and most destructive heavy bomber - the legendary B-52 Stratofortress - under the 25-year “force posture agreement” signed by US Secretary of State John Kerry, Defence Secretary Chuck Hagel and Foreign Minister Julie Bishop and Defence Minister David Johnston during the annual AUSM talks Sydney today.

The 1950s era B-52 is the oldest aircraft in the US air force inventory and is at the leading edge of its strategic nuclear strike capability. The aircraft can carry nuclear warheads to targets anywhere on earth.

The US military has flown two Boeing B-52 bombers into Darwin ahead of multi-national war games hosted by the Australian Defence Force (ADF).

The B-52s, weighing more than 125,000 kilograms each, will form the tactical backbone of a training exercise dubbed Pitch Black, according to military officials.

Two teams made up of men and women from the US armed forces have also arrived in the Top End to take part in the exercise.

The simulated conflict will involve long-range tactics in the vast, empty airspace between Darwin and Katherine.

US Marines began arriving in the Territory on a six-month rotational basis in mid-2012 and have since undertaken joint training exercises with the ADF.

According to a statement, the rotations of US military equipment and personnel in the Pacific region "enhance US ability to train, exercise and operate with Australia and with other allies and partners across the region, further enabling the US to work together with these nations to respond more quickly to a wide range of challenges, including humanitarian crises and disaster relief, as well as promoting security cooperation efforts across the region".

Decisions on future rotations remain under discussion, the statement adds.

The Australian government will begin a multimillion-dollar construction project this month at two military facilities to accommodate future rotations of up to 2,500 US Marines. The project will ensure “appropriate living and working accommodation is available for the US Marine Corps.” The Corps’ presence in Australia’s Northern Territory is expected to increase dramatically next year when, starting in the spring, about 1,200 Marines arrive for six months of training in the region. The last two rotations comprised about 200 Marines. By 2016, the U.S. expects to deploy a full Marine air-ground task force numbering 2,500 personnel, officials have said. To date, the company-size units rotating through Darwin have stayed at Robertson Barracks. But with aviation support in tow next year, about 130 Marines — along with four heavy-lift helicopters — will be stationed at the air force base.

Col. John Merna, the 31st MEU’s commanding officer, said they found Bradshaw, "very austere. .... Any time you can go into a training area that’s an established training area, it’ll be more useful and effective. So more facilities, harder structures, communications — things that are more permanent — [would be] helpful.”

Okinawa officials say US military aircraft have been involved in 44 crashes in the prefecture since its return to Japan from US rule in 1972. One of the most recent incidents occurred at a university near the US Marine Corps Futenma Air Station. In August 2004, a CH-53 helicopter crashed on the campus of Okinawa International University and burst into flames. 3 crew members were injured. In April 1999, a helicopter of the same type crashed into the ocean off the northern coast of Okinawa's main island, killing 4 crew members.

fire at this week's crash site at Yanbaru Forest, Okinawa.