The 2026 Jakarta Treaty shifts Australia–Indonesia defence ties from functional cooperation to deeper strategic alignment, institutionalising high-level consultation while preserving both countries’ autonomy amid regional uncertainty. It could see expanded opportunities for collaboration in areas like maritime security, cybersecurity and defence industry, reflecting growing mutual reliance without formal alliance commitments. But enduring strategic differences and a persistent trust deficit means that the treaty’s success will depend on whether both parties can sustain transparent cooperation without reigniting historical tensions.

The signing of the Australia–Indonesia Treaty on Common Security (the ‘Jakarta Treaty’) on 6 February 2026 during Australian Prime Minister Anthony Albanese’s visit marks more than just a diplomatic highlight. It signals the start of a new strategic episode in the long-standing and often turbulent relationship between Indonesia and Australia.

In a region becoming increasingly defined by US–China competition, entangled in a web of defence pacts and with fears of maritime insecurity heightened by US withdrawal from its regional security commitments, this treaty offers an anchor of stability in a volatile sea.

For Australia, deepening defence ties with its largest neighbour represents a pragmatic move to diversify its security architecture beyond its traditional reliance on the United States. As Australia’s bridge to Southeast Asia and beyond, Indonesia is a prerequisite to Australia’s own security. For Indonesia, the treaty is a masterclass in strategic hedging, building functional integration while maintaining strategic autonomy.

The Jakarta Treaty marks an upgrade beyond the existing mechanisms within the 2024 Australia–Indonesia Defence Cooperation Agreement — 2+2 meetings, joint military exercises and education and training for military personnel.

While the Jakarta Treaty draws inspiration from the 1995 Lombok Treaty, the underlying logic noticeably differs. The 1995 pact was leader-led, driven more by then-Australian prime minister Paul Keating’s personal ambitions to ‘secure Australia in Asia’ rather than a shared strategic blueprint. This top-down agreement proved fragile, unravelling quickly during the 1999 East Timor crisis. The 2024 agreement represents a more institutionalised framework for deepening defence collaboration, built upon decades of sustained engagement and growing interoperability.

The Jakarta Treaty marks a shift from operational commitments to broader mutual understanding. By institutionalising leader-level dialogue in mandating periodic consultations at head-of-government and ministerial levels, the treaty ensures that defence issues remain a top-tier political priority. It also establishes a formal consultation mechanism, enabling early exchange of assessments and joint deliberations over possible responses to adverse security developments, effectively ending the era of ‘diplomatic surprises’.

And unlike alliance commitments that involve collective defence obligations, the treaty centres on coordinated responses to mutual challenges while protecting each party’s freedom of action. The treaty does not explicitly acknowledge ‘mutual defence’ clauses, preserving Indonesia’s autonomy to upgrade security measures in its southern flank and ensuring each party’s right to hold differing views, including in their ‘threat perceptions’ regarding China. It reflects a maturation of trust where both countries acknowledge that their security is inextricably linked, yet their foreign policy paths remain distinct.

The Jakarta Treaty has the potential to deepen Indonesia–Australia bilateral security cooperation across several areas, including maritime security, cybersecurity, and defence industry. Maritime security will likely remain at the forefront of collaborative efforts, with Indonesia and Australia facing common maritime threats ranging from illegal fishing to grey-zone coercion. Enhanced cooperation could include joint maritime exercises, capacity building for the Indonesian Maritime Security Agency and coordinated patrols to strengthen maritime domain awareness.

Cybersecurity represents another growing domain for collaboration. Hybrid threats like cybercrime and disinformation campaigns require joint attention due to their potential to cripple critical national infrastructure. Given Australia’s well-established cybersecurity capabilities, cooperation through information sharing and joint cyber exercises will be vital in supporting Indonesia’s cyber resilience.

An underexplored area of opportunity is defence industry collaboration. In line with Indonesia’s defence modernisation agenda, the treaty could pave the way for technology transfers and joint development of defence equipment.

But at the strategic level, a fundamental divergence in outlook persists. Australia remains firmly anchored in alliance-based security frameworks like AUKUS and the Quad, while Indonesia has traditionally approached minilateralism with caution, prioritising strategic autonomy and a regionalism grounded in ASEAN centrality.

And despite current optimism, history teaches us that Indonesia–Australia relations are prone to sudden chills — the consequence of a ‘trust deficit’, rooted in sovereignty-related baggage. For many in the Indonesian military, the memory of past friction runs deep — from the suspension of defence ties during the 1999 East Timor crisis to the 2013 wiretapping scandals involving then-Indonesian president Susilo Bambang Yudhoyono and perennial sensitivities over Papua. Sovereignty remains a clear ‘red line’ and actions interpreted as encroaching on Indonesia’s internal matters could freeze cooperation instantly.

These differing strategic orientations raise questions as to how far Indonesia can foster defence cooperation with Australia without challenging its long-standing ‘free and active’ foreign policy doctrine. While Jakarta has signalled that high-level mobility is only ‘temporary’ and ‘collaborative’ rather than ‘foundational’, increasing Australian troop rotations and reciprocal access to military installations could be seen as toeing the ‘red line’. This has prompted debate about whether Indonesia may be moving closer to a Western-aligned security architecture and if it can preserve strategic autonomy while deepening operational cooperation.

The 2026 Jakarta Treaty represents a sophisticated framework for good-faith communication and confidence-building. But to counter the longstanding ‘trust deficit’, both countries must translate these words into concrete action. This requires developing transparent communication mechanisms to manage differences before they escalate into diplomatic crises, including in the form of 1.5-track policy dialogues.

If executed with sincerity, the treaty could represent the moment two neighbours decided that their shared security was too important to be left to the whims of great power politics, marking a bold step towards a more stable, predictable and sovereign Indo-Pacific.

By:
Marina Ika Sari is a Coordinator and Researcher at the ASEAN Studies Program, The Habibie Center.
Dion Maulana Prasetya is an Assistant Professor in the Department of International Relations at Universitas Muhammadiyah Malang.

This article was published in East Asia Forum on April 3, 2026.

https://doi.org/10.59425/eabc.1775253600

EAF | Defence | Indonesia and Australia step up defence cooperation