By Robbin Laird
The recent Australia–Indonesia Defence Cooperation Agreement and the expansion of Exercise Keris Woomera have largely been framed as a bilateral story: two neighbours with a complicated history discovering that they now need each other to manage the shared archipelagic space between them. That framing is accurate as far as it goes. But it leaves out a third actor whose influence is woven through nearly every aspect of what Australia brings to the littoral and, by extension, what Indonesia is now seeing and absorbing.
The United States Marine Corps is the unspoken third leg of a co-invention triangle linking US, Australian, and Indonesian amphibious practice. It does not appear in the order of battle for Keris Woomera. Its flag is not on the beach. Yet the intellectual and operational DNA of the exercise traces back, in substantial measure, to a decade of sustained Marine engagement in northern Australia and across the Indo-Pacific.
The USMC in the Background: Concepts and Presence
Formally, Keris Woomera is an ADF–TNI activity nested within Australia’s Indo-Pacific Endeavour deployment, not a US-led exercise. Both Canberra and Jakarta are deliberate about this framing. Each has compelling reasons to demonstrate that it can plan and execute complex amphibious operations without Washington in the lead.
But deliberate framing does not change operational reality. Over the past decade, Marine Rotational Force–Darwin has made northern Australia a sustained laboratory for US and Australian experimentation in expeditionary operations—from traditional amphibious assaults to humanitarian assistance and disaster relief scenarios. The same Marine Corps wrestling with Expeditionary Advanced Base Operations, stand-in forces, distributed fires, and contested logistics has been shaping how the ADF thinks about land power in the littoral.
The evidence is not subtle. Australian Army work on littoral operations, and the creation of a new Littoral Manoeuvre Group, sit squarely within this intellectual ecosystem. ADF amphibious standard operating procedures, command and control constructs, and scenario design have been refined through repeated contact with Marines during Talisman Sabre and related bilateral activities. Those are precisely the tools and mental models now being applied in Keris Woomera alongside Indonesia.
Trilateral Practice: The Same Beaches, Different Flags
Beyond doctrine, there is concrete trilateral practice that ties the USMC, ADF, and TNI together even when they are not all on the same manifest.
In US-led exercises such as Super Garuda Shield, Indonesia hosts a multinational force, including U.S. Army and Marine elements and at times Australian participants—for combined armour and amphibious training along the East Java coast. Marine Rotational Force–Darwin has run humanitarian-oriented amphibious training alongside ADF and TNI elements in northern Australia, developing shared skills in civil-military coordination and disaster relief that map directly onto the second-phase scenarios of Keris Woomera.
These activities form a lattice of shared experience. Marines are often present when Australians and Indonesians first attempt something difficult together, or they serve as the reference point against which a given evolution is benchmarked. Keris Woomera then becomes the venue where Australia and Indonesia attempt to reproduce or adapt that practice in a deliberately non-US-led environment—retaining the concepts while asserting the bilateral relationship.
Co-Invention Across Three Lanes
The result is a three-lane co-invention cycle in which ideas, people, and techniques flow continuously across overlapping relationships.
In the U.S.–Australia lane, USMC and ADF experiment with EABO-style concepts, land-based anti-ship fires, and distributed command and logistics from bases in northern Australia, supported by platforms such as the Amphibious Combat Vehicle and Australian LHDs. In the U.S.–Indonesia lane, Super Garuda Shield and related training expose the TNI to US joint and amphibious standards across coastal East Java. In the Australia–Indonesia lane, the Defence Cooperation Agreement and Keris Woomera apply a carefully selected subset of these techniques in a bilateral setting that foregrounds archipelagic geography and political sensitivity—with Australia in the lead and Indonesia as full partner.
This is not a formal program.. It is an emergent property of overlapping exercises and relationships. The USMC provides a conceptual and technical impulse; the ADF adapts it to Australian strategy and geography; Indonesia engages with the adapted model while retaining a direct line into U.S. practices through its own bilateral access. The co-invention is genuine on all sides—each partner is transforming what it receives rather than simply replicating it.
Advantages and Frictions
This triangular arrangement carries real advantages and frictions that are often glossed over.
On the positive side, it accelerates learning at every node. Indonesian officers and NCOs are not merely absorbing Australian methods; they are absorbing a hybrid of USMC and ADF practice filtered through their own archipelagic requirements. That gives Jakarta a richer menu of options as it seeks to professionalise the TNI and modernise its amphibious and coastal forces. For Australia, the ability to demonstrate that its littoral formations can operate effectively with both the USMC and the TNI with compatible procedures and shared scenario design is a powerful operational and political asset. It positions the ADF as a connector force capable of knitting together U.S. and regional partners in precisely the spaces that matter most to Australian defence strategy.
But tensions exist. The more USMC concepts drive the ADF’s amphibious transformation, the greater the risk that Australian–Indonesian cooperation will be read in Jakarta as an extension of U.S. force-posture objectives, especially if trilateral activities are not carefully calibrated. Indonesia’s longstanding sensitivity to foreign basing arrangements and formal alliance structures has not disappeared. The Defence Cooperation Agreement and Keris Woomera are framed as mutual capacity-building and military diplomacy precisely to reassure Indonesian domestic audiences that they are not backdoor alignment mechanisms.
Equally, U.S. planners will need to accept that some of the most strategically significant littoral work in the Australia–Indonesia nexus will occur without U.S. flags on the skyline. That is a feature, not a deficiency, of a maturing regional security architecture. Washington’s concepts travel furthest when local partners can adapt and own them.
Where the USMC Piece Goes Next
Looking forward, three areas stand out where the USMC’s role in this triangular story could deepen, if politics, resources, and trust align.
The first is littoral fires and sea denial. Marines and Australian forces are already experimenting with land-based anti-ship missiles and dispersed firing units in northern Australia. Bringing Indonesian observers and eventually small units into selected aspects of that experimentation, within the limits of U.S. export and technology-transfer constraints, would directly shape TNI thinking about coastal defence and archipelagic sea-denial.
The second is distributed humanitarian and civil-military operations. Trilateral HADR exercises out of Darwin provide a politically comfortable setting to refine distributed command, logistics, and information-sharing under operational stress. The same architectures that move aid and evacuees can, with different payloads and permissions, move precision weapons and reconnaissance assets. In this space, USMC, ADF, and TNI officers are already building a shared mental model of how to manage complexity and contested access in littoral environments.
The third is professional military education. More Indonesian officers moving through courses and attachments that expose them simultaneously to USMC and ADF perspectives would institutionalise the co-invention process rather than leaving it dependent on episodic exercises. That is where ideas about EABO, littoral manoeuvre, and archipelagic defence can be debated, contested, and genuinely adapted, rather than transmitted as finished product.
A Quiet but Consequential Role
In public messaging, Keris Woomera will continue to be presented as a story about Jakarta and Canberra building trust across a historically complicated relationship. That story is true and important. It deserves to be told on its own terms.
But underneath it, the U.S. Marine Corps plays a quiet and consequential role: providing much of the conceptual grammar and operational experience from which both the ADF and the TNI are constructing their own amphibious dialects. The exercise is bilateral in ownership and presentation. The intellectual foundation is trilateral in character.
If Australia and Indonesia are co-inventing amphibious power in the archipelago, they are doing so in a workshop whose tools, blueprints, and many of the instructors carry a USMC stamp whether or not the eagle, globe, and anchor is visible on the beach on any given day.
Bibliography
ABC News (Australia). “Indonesian Army Joins Australian and US Forces for Humanitarian Disaster Training in the Northern Territory.” May 18, 2022.
https://www.abc.net.au/news/2022-05-19/nt-australian-indonesian-us-defence-training-operation/101076206
ABC News (Australia). “US Marines Join Aussie and Indonesian Troops for Training in the Northern Territory | Exercise Crocodile Response.” Video, May 23, 2023.
https://www.youtube.com/watch?v=hrSndiIucrs
Australian Army. “The Cove Theme 2026: Littoral Operations.” March 2, 2026.
https://cove.army.gov.au/article/cove-theme-2026-littoral-operations
Australian Army Research Centre. “Where the Shore Meets the Sea.” August 3, 2022.
https://researchcentre.army.gov.au/library/land-power-forum/where-shore-meets-sea
Australia Department of Defence. “Australia, United States and Indonesia Work Together in Top End Disaster Exercise Bhakti Kanyini AusIndo 2024.” Media release, August 13, 2024.
https://www.defence.gov.au/news-events/releases/2024-08-13/australia-united-states-indonesia-work-together-top-end-disaster-exercise
Australia Department of Defence. “Marine Rotational Force – Darwin.” Defence Activities, updated May 2, 2024.
https://www.defence.gov.au/defence-activities/programs-initiatives/united-states-force-posture-initiatives/marine-rotational-force-darwin
Australia Department of Defence. “ADF Successfully Completes Interoperability Training in Indonesia.” Media release, September 13, 2023 (Exercise Super Garuda Shield 2023).
https://www.defence.gov.au/news-events/releases/2023-09-14/adf-successfully-completes-interoperability-training-indonesia
Defence News. “U.S. Marines Train Beach Landings Down Under with Old Allies, New Rides.” July 31, 2025.
https://www.defensenews.com/global/asia-pacific/2025/08/01/us-marines-train-beach-landings-down-under-with-old-allies-new-rides
Marine Corps University. “Land Power in the Littoral.” Journal of Advanced Military Studies 15, no. 2 (2024).
https://www.usmcu.edu/Outreach/Marine-Corps-University-Press/MCU-Journal/JAMS-vol-15-no-2/Land-Power-in-the-Littoral
Military Times. “In U.S.-Led Drills, Australian and Indonesian Forces Deploy Battle Tanks.” September 9, 2023.
https://www.militarytimes.com/news/your-military/2023/09/10/in-us-led-drills-australian-and-indonesian-forces-deploy-battle-tanks
United States Navy Institute News. “Australia, Indonesia Drill Together in Major Amphibious Exercise.” November 19, 2024.
https://news.usni.org/2024/11/20/australia-indonesia-drill-together-in-major-amphibious-exercise
United States Marine Corps Forces, Pacific. “U.S., Indonesia and Australia Train Together during RIMPAC.” Photo feature, July 24, 2016.
https://www.marforpac.marines.mil/Photos/igphoto/2001581852