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 remarked, 'We have told them that Australia is our security partner of choice and they understand our alliances here.'
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'.
The deal covers greater collaboration around cyberspace and electromagnetic warfare and includes annual joint military exercises.
This agreement will also help address Australia's recent struggles with military recruitment, according to experts. 'PNG has an oversupply of able-bodied citizens who are willing to do this kind of work,' said Nobetau.
While the deal is expected to modernize PNG's military, concerns remain regarding its implications for PNG's independent foreign policy and potential costs associated with its alignment with Australia against China.