Indonesia, Australia, Japan and PNG Expand Security Ties Amid Regional Shifts
A month after formalizing a landmark security treaty, Indonesia and Australia are broadening their security cooperation to include Japan and Papua New Guinea, signaling a recalibration of regional defense strategies in the Indo-Pacific. The move reflects a growing trend toward minilateralism as nations seek to bolster stability amidst increasing geopolitical competition.
Expanding Trilateral Frameworks
Indonesian Defense Minister Sjafrie Sjamsoeddin announced the plan following a meeting with his Australian counterpart, Richard Marles, in Jakarta on March 12, 2026. Two new trilateral security arrangements are envisioned: one encompassing Indonesia, Australia, and Japan, and another between Indonesia, Australia, and Papua New Guinea. According to Sjamsoeddin, the expansion focuses specifically on “defense professionalism.” [The Diplomat]
Minister Marles characterized the proposed cooperation as “a really important piece of architecture” for advancing peace and stability in the region. [The Diplomat] He highlighted the strong momentum in the growing defense relationship between Australia and Indonesia, aimed at supporting a secure and peaceful Indo-Pacific. [The Diplomat]
The Jakarta Treaty and Enhanced Bilateral Ties
This expansion builds upon the recently signed Australia-Indonesia Treaty on Common Security – often referred to as the Jakarta Treaty – which commits both nations to increased security consultations. [Al Jazeera] The treaty revives a 1995 security agreement initially signed by President Suharto and Prime Minister Paul Keating. Key provisions include the development of joint military training facilities in Indonesia and increased intelligence sharing, with consultations occurring at both leader and ministerial levels. [Al Jazeera]
Morotai Island as a Potential Training Hub
Discussions also centered on the potential development of a defense training facility on Morotai Island in North Maluku province, Indonesia. [Al Jazeera] Morotai, a former Japanese base during World War II and later a strategic Allied air base, still possesses an operational airfield. [The Strait Times] While the facility would be owned by Indonesia, Australia sees opportunities for training engagement, and Indonesia is considering access for military personnel from the Philippines and Singapore. [The Strait Times]
Regional Context and Strategic Implications
The expansion of security cooperation aligns with broader regional trends. Australia signed a Mutual Defence Treaty with Papua New Guinea in October and a Reciprocal Access Agreement with Japan in 2022, facilitating joint military exercises. [The Strait Times] Indonesia has also deepened defense ties with both PNG, focusing on border security, and Japan, which has evolved from an economic partner to a key player in maritime security. [The Strait Times]
A trilateral Defense Ministers’ Meeting involving Indonesia, Australia, and PNG was held in Port Moresby in December, emphasizing the importance of trust-building, harmonized approaches, and coordinated responses to regional challenges, including border management, maritime security, and disaster relief. [The Jakarta Post]
These developments are widely seen as a response to the evolving international landscape, characterized by a more assertive China and a perceived shift in U.S. Engagement in the region. [The Diplomat] The proliferation of trilateral and minilateral security agreements is expected to continue as nations seek to navigate these complex geopolitical dynamics.