Australia and Indonesia have substantively concluded negotiations on a new bilateral security pact titled the Treaty on Common Security. The agreement, announced in Sydney, establishes a formal mechanism for the two nations to consult on security matters and potential threats. This new Australia-Indonesia security treaty is designed to expand upon existing defence frameworks, formalising closer cooperation in areas including maritime security, counter-terrorism and humanitarian assistance. The pact is scheduled to be formally signed in 2026.

The Sydney Announcement

The conclusion of negotiations was announced on 12 November 2025 by Australian Prime Minister Anthony Albanese and Indonesian President Prabowo Subianto. The leaders held bilateral talks at Kirribilli House before making a joint statement at a Royal Australian Navy Base in Sydney. President Prabowo, whose trip marked his first visit to Australia since taking office in October 2024, also met with Australian Governor-General Sam Mostyn.

Prime Minister Albanese described the agreement as a “watershed moment” in the bilateral relationship. He stated that the “treaty is a recognition from both our nations that the best way to secure peace and stability is by acting together”.

President Prabowo affirmed the agreement commits both nations to “close cooperation in the defence and security fields”. He referenced Indonesia’s “good neighbour policy”, adding that “Good neighbours will help each other in times of difficulties”. Reports also noted President Prabowo’s reference to Indonesia’s non-aligned foreign policy.

Core Provisions of the Australia-Indonesia Security Treaty

The new treaty institutionalises the security relationship at the highest levels. It is described by the Australian government as a “significant extension” of existing security and defence cooperation.

The Consultation Mechanism

The central element of the treaty is a mutual consultation clause. The pact commits Australia and Indonesia to two main undertakings:

  • To consult at a Leader and Ministerial level on a regular basis regarding matters that affect their common security.
  • To consult with each other if the security of either or both nations is threatened. Following this consultation, they will “consider what measures may be taken either individually or jointly” to address the threat, in accordance with the processes of each government.

Building on Existing Frameworks

This 2025 treaty builds upon several preceding agreements, including the 2006 Lombok Treaty and a Defence Cooperation Agreement (DCA) signed in 2024. The 2024 DCA already pledged closer cooperation and included provisions for military personnel from each nation to operate in the other’s territory.

According to a statement from the Australian Minister for Foreign Affairs, the new treaty is “modelled closely” on the 1995 Agreement on Maintaining Security. That 1995 agreement was subsequently withdrawn by Indonesia in 1999 following Australia’s leadership of a United Nations peacekeeping mission in East Timor.

Scope of Future Cooperation

Beyond the high-level consultation mechanism, the treaty aims to promote “mutually beneficial cooperative activities in the security field”. It is expected to enhance practical cooperation and improve interoperability between the Australian Defence Force (hereinafter: ADF) and the Tentara Nasional Indonesia (hereinafter: TNI), the Indonesian National Armed Forces.

According to an Australian parliamentary inquiry report from earlier in 2025, the underlying Defence Cooperation Agreement supports a complex relationship involving around 20 annual joint exercises. The new treaty is expected to strengthen cooperation in specific areas, including:

  • Maritime security
  • Counter-terrorism
  • Humanitarian and disaster relief
  • Logistics support
  • Defence industry
  • Education and training

The ADF’s Defence Cooperation Program offers approximately 110 places for TNI personnel in Australian training courses each year, which is a key component of building this interoperability.

Next Steps for Ratification

With negotiations “substantively concluded,” both nations will now undertake their respective domestic processes to approve the treaty. For Indonesia, this is expected to involve a parliamentary approval process and the development of new implementing legislation. Prime Minister Albanese stated that he expects to travel to Indonesia in January 2026 to formally sign the treaty.

Outlook for Regional Security

The formalisation of the Australia-Indonesia security relationship through this treaty presents a clear commitment by Australia to position itself as a diplomatic force in the region, given a recently signed defence treaty with Papua New Guinea. It moves Australia’s partnerships beyond ad-hoc cooperations and grounds it in a legally significant, binding structure. This development suggests a shared assessment by both governments that a stable bilateral relationship is a primary asset in navigating regional geopolitical dynamics.

The treaty solidifies the Australia-Indonesia relationship as a distinct and foundational element of the Indo-Pacific security architecture. By creating a formal obligation to consult during a crisis, both nations are signalling that their “common security” is intrinsically linked and merits a permanent, high-level diplomatic and military channel.

For Indonesia, as well as Papua New Guinea, the defence architecture built with Australia constitutes a sustainable approach to China’s expansion in the region. Both nations position themselves clearly on the side of Australia, potentially paving the way for other nations to join in closer cooperation with Australia. Moreover, the treaties could open the door for cross-national treaty infrastructures to shield Oceania from Chinese influence.