By Brad Ryan in Washington DC, for ABC
Anthony Albanese, Joe Biden and Rishi Sunak announced further details of AUKUS in March 2023. Photo: AFP / Jim Watson
Australia and its AUKUS partners, the US and UK, are considering including Japan in some of the alliance's military projects, the three countries have confirmed.
But they have stopped short of announcing a formal expansion of the AUKUS partnership, which has been the subject of ongoing speculation and was flagged by the US ambassador to Japan last week.
China, which has long opposed AUKUS, responded by saying it was "gravely concerned" about the prospect of Japan joining the pact.
Its foreign ministry warned such a move would "intensify the arms race in the Indo-Pacific region and disrupt regional peace and stability", the South China Morning Post reported.
In a joint statement, the AUKUS countries' defence ministers said they had always intended to "engage others in Pillar II" of the alliance.
"Pillar II" represents a plan to share technology and jointly develop and provide military capabilities, with a focus on security in the Indo-Pacific region to counter Chinese aggression.
"Our objective remains to further the delivery of advanced military capabilities to our respective defence forces in support of regional stability and security," the defence ministers' joint statement said.
"We are confident that engaging like-minded partners in the work of Pillar II will only strengthen this pursuit.
"Recognising Japan's strengths and its close bilateral defence partnerships with all three countries we are considering cooperation with Japan on AUKUS Pillar II advanced capability projects."
The AUKUS pact was announced by then-prime minister Scott Morrison and his US and UK counterparts in late 2021. "Pillar I" of the deal, which would not involve Japan, is a plan to arm Australia with nuclear-powered submarines at a stated cost of up to A$368 billion (approx NZ$402b) over three decades.
Chinese foreign ministry spokeswoman Mao Ning said Beijing "opposes the formation of exclusive 'small circles' and the creation of bloc confrontation", according to the South China Morning Post.
"Japan, in particular, should deeply learn from historical lessons and exercise caution in military security," Mao said.
Japan's involvement in AUKUS is likely to feature in talks between Japanese Prime Minister Fumio Kishida and US President Joe Biden when they meet in Washington on Wednesday.
White House national security spokesman John Kirby said the state visit would build on "the immense progress between our two nations to help create a safer and more secure Indo-Pacific".
"You'll be hearing more from us soon, obviously, on the wide range of deliverables that will be announced by the leaders on Wednesday," he said.
The White House will also host a trilateral leaders' summit between Biden, Kisihda and Philippines President Ferdinand Marcos Jr on Thursday.
This story was first published by the ABC.