The Pukpuk Treaty: A New Security Architecture in the Indo-Pacific

On 17th of September 2025, Australia and Papua New Guinea (PNG) signed a mutual defence treaty titled the Pukpuk Treaty. The treaty stands to systematically change the foreign and defence policy of PNG while ensuring its protection by Australian forces.

Australia’s historic role as a regional hegemon in its neighbourhood is increasingly challenged by China. In that context, the Pukpuk Treaty protects Australia’s influence and power by ensuring that the strategically placed country of PNG remains within Australia’s sphere of influence.

Strategic Context

The Pukpuk Treaty was signed during a time of increasingly active contention between the United States and its allies on one side and China on the other. Australia stands as a faithful ally to the United States as well as orientating its defence strategy primarily against China. Increasingly, China is trying to elevate its power and influence in the region by trying to assert its territorial claims in the South China Sea as well as gain influence in the Indo-Pacific.

China’s efforts have displaced Australian political influence, notably in the Solomon Islands, to which Australia has been a traditional security partner and had at one point deployed a contingent of police and military personnel as part of the Regional Assistance Mission to Solomon Islands (RAMSI), each individually larger than the whole of the Solomons’ security forces. However, with the signing of the China-Solomon Islands Security Agreement, the text of which is not public, China is understood to have taken on the role of internal security guarantor for the Solomons as well as gaining the ability to use the country as a supply base. At the same time, the islands have been reticent to let US and British ships dock in its ports, signalling a clear rebuke to the US and its allies.

The Solomon Islands and PNG matter to Australia because of their geographic locations, which form a natural shield for Australia. Any adversary aiming to attack Australia from the North would likely pass by these territories to reach Australia, and at the same time these territories are ideal staging grounds for any potential attack on Australia. This reality has been historically recognised with the Territory of New Guinea; a League of Nations Mandate and later United Nations Trust Territory being assigned to Australia specifically classed as a Strategic Trust Territory. The Solomon Islands were a British protectorate never officially administered by Australia. However, a transfer to the Commonwealth of Australia was considered but never done due to financial concerns.

The Pukpuk Treaty

The primary provisions of the new treaty are the mutual defence clause, the recruitment clause allowing Australia and PNG to recruit each other’s nationals and the non-interference clause, preventing both countries from entering any partnerships with other countries which might run counter to the purpose of the Pukpuk Treaty.

With PNG entering an arrangement that includes a mutual defence clause, it forgoes its traditional neutrality in favour of a formal relationship with Australia. This is significant, as the former Australian-administered territory has long relied on Australia for assistance in security, as well as being a major recipient of development aid, but has avoided formal commitments to Australia. In political discourse, Australia sometimes even refers to PNG as its “family”, illustrating the close political connection between the countries. Despite PNG’s close relationship and arguable dependence on Australia, PNG had previously chosen to be uncommitted. The newly signed treaty ends this ambiguity and ensures that PNG is firmly on the side of Australia in any potential conflict.

The Pukpuk Treaty also faces some criticism, especially in provisions that might impact future cooperation. Parties to the treaty are specifically obligated not to cooperate with other countries in a way that might be detrimental to the treaty’s purpose of maintaining the security of Australia and PNG. This means that PNG could not enter into an arrangement like the Solomon Islands had, which would enable an adversary of Australia to use the country as a military base or engage in other activities to weaken Australia’s security and defence posture. The treaty’s impact on PNG’s ability to engage in security cooperation with other powers has especially been criticised by China, whose opportunities to gain a strategic foothold in PNG are now significantly diminished.

The treaty permits Australia to recruit Papua New Guineans into its armed forces, potentially alleviating its recruitment shortages. Australia struggles to fill its ranks of armed forces, and the prospect of Australian salaries and eventual citizenship is likely to entice a number of PNG nationals to apply to the Australian Defence Forces (ADF). Given that Australian salaries are significantly higher than PNG salaries, it is unlikely for Australians to join the PNG Defence Forces. The ADF is thought to aim to recruit up to a total of 10,000 PNG nationals, a significant number for a force which currently stands at less than 60,000 strong. An increase in size of this magnitude would have a significant impact on the ADF’s military capacities, making Australia a more potent player in the Indo-Pacific.

Wider Consequences

Australia has reinforced its defence posture with this treaty and ensured that PNG remains in its area of influence while frustrating China’s bid for power in the region. Denying such a strategic area to China will ensure that Australia has comfortable separation from the Middle Kingdom, meaning that during a potential conflict with the US, Australia will remain a thorn in China’s side. Similar to how PNG and the Solomon Islands could be a shield for Australia, they could also be used to contain the ADF and prevent (or at least make it significantly more difficult for) them to engage in operations alongside the US without passing through the Chinese-controlled South China Sea.

PNG is no longer a place of significant competition for China and Australia, clearly having chosen a side. PNG’s security is now assured by Australia, and the fragile state can now surely rely on Australia’s support in dealing with its security challenges. The Pupuk Treaty stands to significantly improve Australia’s position in the region while leaving China locked out of a strategically important country. The treaty’s legacy will likely have long-standing consequences on the dynamics of the Indo-Pacific and be a vital part of Australia’s geostrategic security efforts.

Written by Titus Hiller, Edited by Hannah Shaffer

Photo Credit: Nico Smit (uploaded February 11, 2023) on Unsplash.