Australia on Monday signed an agreement with the United States and Britain formalizing access to classified nuclear submarine information under their so-called AUKUS security partnership.
The Exchange of Naval Nuclear Propulsion Information Agreement is the first embodiment of the three-way arrangement announced in September under which Australia looks to acquire nuclear-powered submarines amid China's growing maritime power.
The agreement will allow the United States and Britain to share their nuclear submarine secrets with a third country for the first time.
"This Agreement will support Australia in completing the 18 months of intensive and comprehensive examination of the requirements underpinning the delivery of nuclear-powered submarines," Defense Minister Peter Dutton said in a statement.
The agreement will also provide a mechanism for Australian personnel to access training and education from their U.S. and British counterparts on how to safely and effectively build, operate and support nuclear-powered submarines, the statement said.
China immediately lambasted the agreement, saying it would deliberately aggravate tensions in the Indo-Pacific region, stimulate an arms race, threaten regional peace and stability, and undermine international nonproliferation efforts.
"Many countries have expressed serious concern about the possible negative consequences" of the agreement, Chinese Foreign Ministry spokesman Zhao Lijian told reporters in Beijing.
Australia once again stressed that the agreement does not breach its international obligations on nuclear nonproliferation, noting that the accord only allows for the sharing of naval nuclear propulsion information and the submarines will be conventionally armed.
Australia's move to acquire eight nuclear-powered submarines under the AUKUS security partnership has led to a diplomatic falling-out with France, as it resulted in Canberra ditching a contract for 12 French diesel-powered submarines.