The Cambodia–Thailand Clash and the Shadow of Great Power Attention

Mirielle Augustin | Indo Pacific Fellow

Image sourced from Chamrat Charoenkhet via Wikimedia Commons.

In July 2025, rare armed clashes between two ASEAN member states, Cambodia and Thailand, disrupted the bloc’s long-standing intra-regional peace. Exchanges of gunfire near the Ta Moan Thom temple marked the most serious escalation between the two countries in more than a decade. What followed was a flurry of quiet diplomacy led by Malaysia, alongside quick attempts by external powers to insert themselves into the process and frame the outcome as part of their own influence. ASEAN’s ability to manage conflict within its ranks was back in focus, but so too was the question of how much space remains for it to do so in an Indo-Pacific crowded by great power competition.

A Historical Dispute

At the heart of the fighting lies one of the most intractable issues in mainland Southeast Asia: who can lay claim to the centuries-old Hindu temples along the Cambodia–Thailand border that date back to the ancient Khmer Empire. The Preah Vihear temple, perched on the Dangrek escarpment, has been a flashpoint for conflict since the International Court of Justice awarded it to Cambodia in 1962, a ruling Thailand has never fully accepted. The disagreement is compounded by incompatible cartographic traditions: Cambodia uses old French colonial maps at a 1:200,000 scale, while Thailand prefers its own, far more detailed 1:50,000 scale charts. These differences, while technical on the surface, are central to and inseparable from nationalist narratives on both sides.

The origins of the dispute trace back to early 20th-century treaties between Siam and French Indochina, which left sections of the border undemarcated. Sporadic clashes in the late 2000s and early 2010s killed dozens and displaced tens of thousands. While the immediate causes of the July flare-up were localised, the underlying tensions have never been fully addressed and are unlikely to be resolved soon.

Malaysia Steps In

As ASEAN chair, Malaysia moved quickly to offer mediation. With officials from China, the United States, and other ASEAN states invited to observe, the talks reflected both ASEAN’s willingness to act and the reality that external powers were present and watching closely. Within days of the clashes, Prime Minister Anwar Ibrahim invited both governments to talks in Putrajaya. His personal approach to diplomacy helped open channels for dialogue, supported by the quiet work of the Malaysian foreign ministry. By the end of the week, both sides had agreed to a ceasefire.

The agreement included plans for a Malaysian-led observer mission, a step seen as crucial for preventing further incidents. A similar attempt to deploy Indonesian monitors in 2011 had never materialised.

Malaysia’s approach showed the advantages of having a leader with strong personal networks in both countries, helping to open channels quickly in a tense environment. At the same time, it also highlighted the importance of ensuring these efforts are supported by broader ASEAN processes, and ensuring international buy-in, so that conflict resolution does not depend solely on individual relationships.

The External Audience

Neither the United States (US) nor China brokered the ceasefire, but both found ways to project their presence into the diplomatic narrative. Washington’s involvement was noisy and transactional. President Donald Trump claimed personal credit for securing the ceasefire, even linking it to the resumption of tariff negotiations.

Meanwhile, Beijing’s posture was quieter. China expressed sympathy for casualties on both sides, reiterated support for ASEAN processes, and sent diplomatic observers to the talks. Officially, it maintained a “fair and impartial” position. Yet its preference for legal arbitration aligned closely with Cambodia’s stance, a reflection of its deep political and economic ties with the country. While less overt than Washington’s approach, this too was a form of signalling.

These moments illustrate a wider reality: in today’s Indo-Pacific, even conflicts confined to ASEAN’s own members are rarely insulated from the attentions of larger powers. Each seeks to shape the narrative, if not the outcome, in ways that serve its broader regional strategy.

ASEAN’s Balancing Act

The ceasefire was a diplomatic success for Malaysia and, by extension, ASEAN. It demonstrated that the bloc can act meaningfully when internal disputes threaten to escalate. Yet the cracks are hard to ignore. ASEAN’s long-held principle of non-interference is increasingly strained in the face of militarised nationalism, humanitarian risk, and online disinformation campaigns that can inflame tensions long after the shooting stops.

The episode also underscores a structural challenge: ASEAN must be able to resolve its own disputes while managing great power attention. If it cannot take the lead, it risks becoming less a platform for collective action than a stage on which external actors perform their own diplomacy.

Looking Ahead

The Cambodia–Thailand clash offers a warning and an opportunity. Without stronger preventive diplomacy, tools that allow ASEAN to respond rapidly to crises, share resources across members, and coordinate limited security measures, the bloc will remain reactive rather than proactive. With such a posture, even successful interventions will be vulnerable to external framing.

But this does not mean shutting out great powers entirely. External engagement, if invited and managed on ASEAN’s terms, can add resources and political heft. The challenge is ensuring it complements, rather than overshadows, ASEAN’s own leadership.

A Final Thought

In the end, the ceasefire between Cambodia and Thailand was more than a resolution to a localised dispute. It was a reminder that ASEAN’s credibility rests not only on its ability to keep peace among its members, but on its capacity to do so in full view of, and in dialogue with, the great powers that observe its activity. In this crowded diplomatic space, the difference between being a platform and being a playground may depend on how deftly ASEAN can hold its own peace.

Mirielle Augustin is the Indo Pacific Fellow for Young Australians in International Affairs. She is completing a Bachelor of Philosophy (Honours)-Humanities and Social Sciences and a Diploma of Languages at the Australian National University. Of East Timorese and Malaysian heritage, she grew up across France, Mauritania, Cameroon, Timor-Leste and Australia, which has shaped her passion for public policy, cultural diplomacy, and multilingual engagement.

Mirielle has studied and worked abroad in France and Indonesia, including programs supported by DFAT’s New Colombo Plan, and the Australia-Indonesia Youth Exchange Program in 2024. Through this Fellowship, she hopes to explore how international affairs can better reflect the lived realities of Indigenous and marginalised communities.