The US, Australia and Britain unveiled details of the Aukus plan to provide Australia with nuclear-powered attack submarines from the early 2030s to counter China's ambitions in the Indo-Pacific.

Submarine number 841 – named Hero Kim Kun Ok after a North Korean historical figure – will perform its combat mission as 'one of core underwater offensive means of the naval force' of North Korea, Kim says.

North Korea has reacted angrily, saying such a deployment could meet the criteria for its use of nuclear weapons.

The moves by the US to introduce strategic nuclear assets to the Korean peninsula is a blatant nuclear blackmail against North Korea and regional countries and presents a grave threat to peace, KCNA says.

Anthony Albanese says the deal is necessary given the buildup of Chinese military power in the region.

While Australia has ruled out deploying atomic weapons, its submarine plan marks a significant new stage in the confrontation with China.

This follows an acrimonious row between the countries over a submarine contract last year.

Prime Minister Anthony Albanese says the French firm has agreed to a 'fair and an equitable settlement' of US$584 million for Australia ending a decade-old multi-billion-dollar submarine contract.

Australia Defence Minister Richard Marles says the comments are 'loose' and undermine the Aukus agreement sealed in September last year.

In exchange for his guilty plea, Jonathan Toebbe is expected to be sentenced to between 12.5 to 17.5 years in prison.

Jonathan Toebbe and his wife, Diana, were arrested on Saturday in West Virginia following a year-long sting operation by undercover FBI agents.

Jonathan Toebbe with access to restricted data on nuclear-powered warships, collaborated with his wife to exchange data on submarine nuclear reactors for around US$100,000 in cryptocurrency.