The new AUKUS alliance was announced this morning by Prime Minister Scott Morrion, US President Joe Biden and UK Prime Minister Boris Johnson with a focus on the wider Indo-Pacific.
The submarines will be built in Adelaide.
Morrison was clear that the subs will be nuclear powered, not nuclear armed and this is not a first step to a wider nuclear power sector in Australia, although separately the government has been publicly mulling the possibilities of small scale reactors since 2018, with limited public support.
The Indo-Pacific as a geopolitical region has been a focus of the US for some years, supplanting the smaller Asia-Pacific as a strategic concept as it seeks to contain a growing, and more aggressive China.
The Quadrilateral Dialogue, between Australia, India, the US and Japan, which involves defence talks and military operations in the Indian Ocean, is part of this.
"The first major initiative of AUKUS will be to deliver a nuclear-powered submarine fleet for Australia," Morrison said this morning.
"Over the next 18 months, we will work together to seek to determine the best way forward to achieve this. This will include an intense examination of what we need to do to exercise our nuclear stewardship responsibilities here in Australia."
The US will help Australia, which has no at-home nuclear capability beyond medicine and low level storage of waste, develop the submarines. Australia is home to the Australia Institute of Nuclear Science and Engineering, which is over 60 years old. The technical challenges of building conventional submarines in Australia has already been considerable.
The shortfin Barracudas Australia commissioned from France in 2014, were to be refitted as diesel-electric. The original French design is nuclear powered; however this deal essetnailly ends that $90 billion deal for 12 subs in two tranches.
Former Labor Prime Minister Paul Keating was scathing this morning in his response to the deal and said it would "amount to a lock-in of Australian military equipment and therefore forces with those of the United States".
When Prime Minister Tony Abbott made the decision in 2014 he plumped for the French over Sweden's Kockums that had designed the former Collins-class subs commissioned by Bob Hawke.
Abbott was originally thought to favour Japan's Soryu-class, and said as much to counterpart Shinzo Abe, for similar interoperability reasons and closer collaboration with the US.
President Bident said there was a need to address both the current strategic environment in the region and how it may evolve.
"Because the future of each of our nations, and indeed, the world, depends on a free and open Indo-Pacific, enduring and flourishing in the decades ahead," he said.
Australia's submarines already have some of the greatest distances of any fleet in the world to travel, but the Indo-Pacific covers a truly vast area and two of the largest oceans on the planet.
Nuclear power obviates the need for refuelling allowing them to travel far greater distances.
Defence minister Peter Dutton is in Washington for yearly defence talks and has said the situation in the Indo-Pacific has "deteriorated".
Greens Party leader Adam Bandt has already unsurpiringly referred to the subs as "floating Chernobyls" though there is no recorded instance of an accident involving a nuclear-powered vessel causing a nuclear incident.