PHOTO: Bob Brewer on Unsplash
On 16 September 2025, Papua New Guineans celebrated independence, marking 50 years since its separation from Australia.
The following day, Prime Ministers James Marape and Anthony Albanese came together in Port Moresby to announce their commitment to the landmark ‘Pukpuk’ defence treaty, the first alliance of its kind for Australia since ANZUS in 1951.
The treaty carries implications not only for Australia’s Pacific strategy and Papua New Guinea’s (PNG) domestic politics, but also for the wider regional power struggle between the United States (US), China and others in the Pacific.
Australia’s defence diplomacy
The non-violent use of military capabilities and resources to pursue foreign policy objectives is known as defence diplomacy, which has become central to Australia’s engagement with the Pacific Islands region.
The focus of defence diplomacy is generally on the use of military support through the Defence Cooperation Program (DCP), Pacific Maritime Security Programme (PMSP) and Humanitarian Assistance and Disaster Relief (HADR). The recently signed Pukpuk treaty with PNG is the latest expression of this strategy.
The treaty highlights two key elements: integrated defence cooperation and mutual defence. It extends Australia’s long-established DCP with PNG by fully integrating the PNG Defence Force (PNGDF) with the Australian Defence Force (ADF). Established right after PNG’s independence, the DCP has founded the defence relationship between the two countries.
The DCP aimed to enhance PNG’s personnel, equipment and infrastructure by providing joint training and exercises, investment in capability and infrastructure and embedding advisors and liaison officers in the PNGDF.
However, beyond these initiatives, the recent treaty introduces a deeper level of integration, which may allow as many as 10,000 Papua New Guineans to serve in the ADF. Another key element in the treaty is a deliberately ambiguous version of NATO’s Article 5, allowing both countries to assist each other in responding to peace and security threats.
Phrases like ‘recognise’ and ‘would act to meet the common danger’ render Article 4 of the treaty intentionally less definitive, unlike NATO’s Article 5, which explicitly requires members to provide armed assistance if a party is attacked. This leaves an uncertainty over whether the treaty enables Canberra and Port Moresby to commit to military action in scenarios that pose a threat to the security of either party.
Regional context and rising tensions
Through Australia’s deployment of DCP to Pacific Island Countries (PICs) since the 1970s, the region is not unfamiliar with defence diplomacy activities. Countries and beyond the Pacific have also expanded their defence engagement in the region.
The Pacific Islands Forum (PIF) has long acknowledged that the growing presence of external powers has made the region’s geopolitical environment increasingly crowded and complex. The US has demonstrated its defence presence in the Pacific Islands region through a combination of cooperative partnerships and direct military deployments, including establishing defence agreements and the construction of military bases across the region.
In addition, since signing a security pact with the Solomon Islands in 2022, China’s presence in the Pacific has also become prominent. Likewise, countries such as New Zealand, and those outside the region like the UK, France and Japan, have also increasingly become engaged with such activities.
Amid intensifying external engagements and the growing competition for influence in the Pacific, Australia’s strategic interest appears to establish itself as PICs’ “partner of choice”. For Canberra, the use of defence diplomacy not only ensures security and stability across the region but also reinforces and projects its strategic influence in the Pacific.
However, PICs view their region as more than an arena for power struggle. As global powers like the US, China, France, Japan and others deepen their engagement, PICs have gained leverage. The PICs are using this opportunity to secure development assistance, economic opportunities and collective bargaining power. PICs claimed to be “friends to all, enemies to none” to increase Pacific regional solidarity.
The Pukpuk Treaty illustrates these two sides of the same coin. While the treaty strengthens defence cooperation and deepens Australia’s security role, it also raises concerns for PNG’s previous partners, particularly China, which has been Port Moresby’s most significant economic and trade partner. The Chinese embassy in PNG cautioned both countries about the potential impact the treaty could have on Beijing and other external parties.
For some, the treaty appears to distance Port Moresby from Beijing. It could further complicate Pacific regionalism if Australia’s bilateral treaty with PNG is perceived as part of a broader strategic denial of China. Thus, while Canberra views the treaty as consolidating its role in the region, Pacific leaders, on the other hand, see it as deepening the pressure to choose sides in an increasingly contested strategic environment.
For the same reason ,Vanuatu halted progress on the ‘Nakamal’ agreement with Australia, as Port Vila expressed concerns that the initiative could undermine China’s efforts to build relationships with the Pacific Islands region.
Port Moresby has ensured that the treaty was not created to the exclusion of any country. At the signing, Marape emphasised that the treaty’s establishment was driven by shared geographic history and the lasting regional ties. However, this treaty implies further complications.
PHOTO: Dominic Kurniawan Suryaputra on Unsplash
Domestic implications
While the treaty is likely to be ratified in Australia’s parliament, the political ramifications in PNG may make achieving the same outcome more challenging.
Domestically, PNG is navigating the Bougainville Island independence process, now scheduled for 2027. A referendum was held in 2019 proposing the island’s independence from Port Moresby. However, six years after the non-binding referendum passed, political negotiations have made little progress toward granting the island full autonomy.
This was not Bougainville’s first attempt at independence. Between 1989 and 1997, violent conflict erupted due to inequalities experienced by the people of Bougainville, intensified by resentment over the exploitation of the Panguna mine. In 1990, Bougainville claimed independence, but this was not internationally recognised. For the first eight years of the conflict, Australia supported the PNGDF with military supplies but refrained from direct intervention.
Only when the 1997 Sandline crisis exposed foreign mercenaries operating in PNG did Canberra reluctantly deploy unarmed military personnel and civil monitors to advance a peace process. The crisis began when former PNG Prime Minister Julius Chan hired Sandline International, a private British-based military consultancy firm, to provide mercenaries and high-tech equipment after Australia had stopped supplying the PNGDF with necessary defence support.
Should events similar to the 1989-97 conflict occur again, the Pukpuk treaty would carry wider implications for Indo-Pacific stability. Following Article 4, the treaty may allow PNG to request Australia’s military intervention sooner than in the past, if another independence-seeking unrest arises and is deemed a threat to PNG’s national security. In doing so, the treaty could compel Australia to take action it was previously reluctant to consider.
The situation is further complicated by Bougainville’s economic interest. The island may seek Chinese investment to reopen its mining operations that were historically exploited by the Australian company Rio Tinto between 1972 and 1989. This may affect how Canberra approaches the issue, particularly in light of the treaty.
The treaty further raised an issue of sovereignty. PNG has been careful to avoid a repeat of the public controversy that arose over the 2023 US-PNG Defence Pact. At that time, the opposition filed a Supreme Court review challenging the constitutionality of the pact on sovereignty grounds, causing significant public debate. This time, Marape had confirmed PNG’s sovereignty remained firmly its own.
The PNG State Solicitor has further clarified that no amendments are required for the treaty to come into force, reducing the risk of legal challenges and public dispute. Beyond PNG, the treaty also carries implications for Indonesia, the country’s only immediate land-border neighbour.
While relations between the two countries have generally been cooperative, any sovereignty dispute could create strategic challenges for Australia. Although such a scenario is unlikely, Jakarta does not see this treaty as trivial. Canberra would need to reassure Indonesia that the treaty not only poses no risk to their security, but that it also maintains the stability of the Indo-Pacific region.
Balancing influence
It is undeniable that the Pacific Islands region has become increasingly important in current geopolitics. China’s pivot to the Pacific, alongside the US’ withdrawal from the liberal international order, has put Australia under pressure to act.
However, the Pukpuk treaty carries implications not only for PNG and Australia but for the Pacific region as a whole. The PIF meeting this year has highlighted how partnerships and alliances stir disputes between the PICs, as seen in debates over Solomon Islands’ decision not to invite Taiwan.
With rising tensions and climate change posing a significant threat to the region, scholars from the Australian Strategic Policy Institute have suggested that Australia should move away from bilateral approaches and instead use its defence diplomacy to support multilateral efforts that strengthen regional institutions and address Pacific priorities.
However, how others in the Pacific Islands region will react to the treaty remains unknown.
