Thai-Cambodian Crisis Shows Promise and Limits of Regional Mediation

By: Andrew Wells-Dang, Brian Harding, and Linh Nguyen

September 29, 2025

On July 24, with the world’s attention elsewhere, a dispute between the ruling families of Thailand and Cambodia erupted into fighting along Cambodia’s northern border that killed dozens and resulted in the temporary displacement of over 260,000 civilians. The following week, Malaysia brokered a ceasefire that has so far held, though tensions remain high. SEAPI experts consider what this outbreak of violence means for conflict prevention and resolution in Southeast Asia.

1. What is the origin of recent border conflicts between Thailand and Cambodia?

Wells-Dang: The two neighboring countries have a history of cross-border incursions. Thailand occupied the western provinces of Cambodia during World War II, and defeated Khmer factions used the Thai borderlands as a base for operations in the 1980s. (The name of a well-known Cambodian town, Siem Reap, means “victory over Thailand”.) In the 2000s, the primary trigger for the Thai-Cambodian conflict was the ancient Preah Vihear temple, which the International Court of Justice has ruled lies on the Cambodian side of the border. The temple’s naming as a UNESCO World Heritage site in 2008 led to nationalist rallies in both countries and repeated border clashes.

More than any specific grievance, however, ultra-nationalist political factions have spurred conflict to serve their own purposes. In Thailand, anti-Cambodian rhetoric has combined with opposition to the Thaksin Shinawatra family, initially by the People’s Alliance for Democracy (PAD) or “yellow shirts”, now by parties linked to the Thai army and monarchy. The leaked recording of a June phone conversation between then-Thai prime minister Paetongtarn Shinawatra, Thaksin’s daughter, and former Cambodian leader Hun Sen backfired, fueling rather than smoothing over the border disputes and leading to Paetongtarn’s dismissal.

Meanwhile, Cambodian prime minister Hun Manet has used the crisis to burnish his own nationalist credentials, and perhaps to distract the public from other ongoing problems such as the proliferation of scam centers and impractical plans to build a shipping canal along the southeastern border with Vietnam. Anti-Thai sentiment forms a convenient foil for accusations by the (now banned) political opposition that the ruling Cambodian People’s Party is too close to Vietnam or to China. In short, border tensions have turned violent when it is in the interests of politicians on both sides to highlight them.

2. How have ASEAN and its current chair, Malaysia, engaged in mediating the conflict?

Harding: Malaysia, as ASEAN Chair, moved quickly to position itself as a neutral broker. Within days, Prime Minister Anwar Ibrahim invited Cambodian Prime Minister Hun Manet and Thai acting Prime Minister Phumtham Wechayachai to Putrajaya, Malaysia’s administrative capital. The 28 July meeting resulted in a joint declaration that announced agreement on an “immediate and unconditional” ceasefire. The talks were intentionally low-profile and outcome-driven. Following the ceasefire, Malaysia convened a General Border Committee meeting in Kuala Lumpur, bringing together defense officials from both sides. This led to agreement on deploying ASEAN observer teams to contested areas, tasked with monitoring the truce, reporting incidents, and providing early warning of potential flare-ups.

Behind the scenes, Malaysian diplomats sought to manage the involvement of - or at least the optics of involvement of - major outside powers. Both Washington and Beijing signaled interest in being involved, which Malaysia managed but also successfully worked to keep the process firmly under ASEAN’s umbrella.

Malaysia being the 2025 ASEAN Chair likely benefitted all parties. Anwar’s decades as a globe-trotting politician gave him personal insight into the stakes and the players, while the Malaysian government’s experience in the Bangsamoro peace process and Thailand’s Deep South meant this was far from Malaysia’s first foray into international mediation. Malaysia’s relative geopolitical neutrality also added credibility. Still, the ceasefire owed as much to battlefield dynamics, domestic political incentives, and quiet external pressure as to Malaysian facilitation. The measure of success will be whether this fragile calm becomes a durable settlement - something ASEAN has rarely delivered in protracted disputes.

3. How are other Southeast Asian countries, China and the United States reacting to the crisis?

Nguyen: While all ASEAN member states have swiftly and unanimously expressed their concerns and called for a diplomatic resolution to the conflict, none has been keen to take on a prominent mediating role alongside Malaysia. The overall response has been cautious, with Indonesia and Singapore encouraging dialogue within ASEAN’s existing frameworks and emphasizing the importance of adhering to international law. The Philippines has warned against any escalation, echoed by Brunei’s call for a peaceful, legal settlement. Myanmar went so far as expressing its confidence that peace would be restored within a short period of time.

The reaction of Vietnam and Laos, both sharing porous land borders with Cambodia and undoubtedly concerned about a potential refugee influx in an escalation scenario, has also been measured. Vietnam has refrained from any direct involvement and issued a brief statement calling for both parties to act with utmost restraint and adhere to ASEAN norms. This response reflects the country’s complex historical sensitivities with Cambodia and the latter’s close ties with China. Laos, in an attempt to preserve its affinity with Cambodia while avoiding antagonizing Thailand, issued a statement emphasizing its good relations with both parties. Neither country took any action to strengthen their borders or mobilize their military.

This overall sentiment shows that ASEAN nations consider the flare-up regionally significant but not urgent, which explains their deference to Malaysia in mediation efforts. This deference also bolsters the appearance of ASEAN unity in a context where China’s shadow looms large and the superpower might step in as a power broker should the bloc show signs of discord. Both Vietnam and the Philippines, facing unresolved maritime disputes with China, are keenly aware of this unwelcome possibility.

Consistent with its preference for quiet influence in Southeast Asia, China’s public engagement was minimal at first with a general call for peace. It only stepped up to broker a peace meeting in Shanghai to reinforce the fragile ceasefire mediated by Malaysia. China denied allegations of supplying weapons to the Cambodian army during the conflict, emphasizing a balanced stance that reflects its interests in maintaining access to the Gulf of Thailand while preserving strong ties with Cambodia. With other geopolitical sensitivities at play, China does not yet see an interest in upsetting ASEAN’s delicate regional balance.

In contrast, the United States has acted in a more assertive manner, with President Trump leveraging tariff threats to nudge the two countries to end the conflict. In line with an America First foreign policy, the United States framed its stance around its economic interests and regional stability in the Indo-Pacific. This interference, perhaps coupled with frustration at China’s reluctance to take sides, resulted in Hun Manet trying to court Trump’s favor by nominating him for a Nobel Peace Prize.

4. What does this violent episode mean for peace and security in the future?

Wells-Dang: In comparison to large-scale interstate conflicts or the continuing civil war in Myanmar, the Thai-Cambodian battles may earn little more than a footnote. But they are a foreboding sign of how a breakdown in global order can lead to the proliferation of small conflicts that add up to a less secure world. No regional or international mechanism was available to deter Thai or Cambodian forces from resorting to violence. ASEAN may have saved face through the Malaysian-brokered ceasefire but showed its weakness in being unable to prevent fighting between two of its members. Singaporean Foreign Minister Vivian Balakrishnan rightly called the conflict “a major setback, not just for peace and stability, but for credibility in ASEAN.”

In contrast, Trump’s tariffs may have played a role in scaring both sides into negotiations. But if the only leverage the United States has lies in the arbitrary application of trade barriers, that is a commentary in itself. Sustainable peacebuilding takes time, patience and cultural understanding. It can’t be done by tweet. Until changes in international politics enable the creation of new structures of conflict resolution, such as an intra ASEAN, ASEAN + or United Nations-led task force with enforcement powers, local disputes will continue to fester. The Thai-Cambodian truce will hopefully hold in the short term, but the underlying problems remain. Unfortunately, there is every reason to expect similar conflicts to flare up in the future, whether between Cambodia and Thailand or along other fault lines in Asia.