Australia will gain access to Papua New Guinea's (PNG) military facilities and troops under a key deal that will see the nations come to each other's aid if either is attacked.
Both governments say the deal was born from a yearslong alliance between the two Pacific neighbours, but experts say it is aimed at countering China's growing influence in the region.
The deal ensures China will not have the same access to infrastructure in PNG as it does in other Pacific Islands, said Oliver Nobetau, project director of the Lowy Institute's Australia-PNG network.
It will allow as many as 10,000 Papua New Guineans to serve in Australia's military, and give them the option to become Australian citizens.
With nearly 12 million people, PNG is the largest and most populous South Pacific nation.
China has already significantly shored up trade with Pacific Island nations in recent years, and is now trying to establish diplomatic and security beachheads across the region.
Australia and its Western allies, including the United States, have been attempting to counter these efforts.
PNG Prime Minister James Marape, who signed this latest agreement with his Australian counterpart Anthony Albanese, stressed the deal was not born out of geopolitics.
Marape stated that PNG has been transparent with China, confirming Australia's status as their security partner of choice.
The Pukpuk Treaty, named after the word for crocodile in PNG pidgin, notes that an armed attack on either country would be dangerous to the other's peace and security, so both should act to meet the common danger.
This innovative partnership includes collaboration on cyberspace and electromagnetic warfare and accommodates annual joint military exercises aimed at enhancing operational readiness and interoperability.
However, the agreement has faced criticism, with concerns about undermining PNG's longstanding policy of neutrality. Some critics argue that the treaty may come at a high cost, given PNG's unique position in the Pacific amid rising global tensions.
