An 18-month joint study with the US and the UK is due to be completed by early next year, but staffers from a high-powered US Senate committee have been visiting Australia for talks this week.

Newly tabled responses to Senate questions on notice show the nuclear-powered submarine taskforce has an approved budget of $120m for the 2021-22 financial year and $180m for 2022-23.

That would include funding for technical studies and travel. It would also cover contributions to other government entities which are supporting the taskforce, such as the Department of Foreign Affairs and Trade and nuclear agencies Ansto and Arpansa.

costs of actually building the submarines are yet to be allocated in the budget

A USA Marine will face court over allegations of assaulting a woman at a popular nightclub in Darwin.

A Marine Rotation Force Darwin spokesman confirmed that a marine stationed from their unit had received a notice from police to appear in court regarding an incident last month.

NT Police confirmed a Darwin woman was assaulted at a popular nightclub, the Landmark Hotel on Roystonea Ave on April 30.

It is understood CCTV captured footage of the alleged incident.

“We are working diligently to determine the facts in this situation, and are complying with all orders, policies, and agencies involved,” the MRF-D spokesman said.

On Tuesday NT Police issued a man with a notice to appear in court for the alleged indecent assault. He will appear in Darwin Local Court on June 16.

The 21-year-old man will face court after being charged over an alleged incident at a bar outside of Darwin.

Northern Territory Police said a 21-year-old man had been issued a notice to appear on Tuesday, following the alleged incident in Palmerston on April 30.

It is unclear if the Marine has been stood down over the allegations.

“MRF-D takes allegations of misconduct seriously and we hold our Marines and Sailors to the highest standards of conduct."

Hundreds of U.S. Marines and sailors, Australian soldiers and Japanese Self-Defense Force members are conducting a major warfighting exercise in Australia.

Shoalwater Bay, where the training is taking place, is an arena for the biennial Talisman Sabre exercise, which involved 17,000 U.S., Australian, New Zealand, Japanese, South Korean and British troops last summer.

Australian politicians reacted with alarm earlier this month after revelations that the Solomon Islands, 1,200 miles northeast of Shoalwater, was negotiating a security pact with China.

Australian Prime Minister Scott Morrison refused to say how his government might respond if China attempted to establish a military base in the islands.

The exercise has taken place each year since 2015.

More than 650 military personnel including US Marines and sailors have joined Japanese and Australian soldiers for a large-scale, live-fire training exercise this month.

The exercise, which will include live firing, comprises 400 Australian Defence Force (ADF) soldiers, 190 US Marines from Marine Rotational Force Darwin (MRF-D) and 70 soldiers from the Japanese Ground Self Defence Force (JGSDF).

It started Monday and is scheduled to take place throughout the heritage-listed, 453,700 hectare Shoalwater Bay Military Training area, about 80km north of Rockhampton in Central Queensland, through to May 27.

Brigadier Michael Say, Commander of the Brisbane-based 7th Combat Brigade, said the combined arms exercise would include tank integration and live fire between infantries.