Pressure from the US is unlikely to resolve the Cambodia Thailand conflict

The fragile peace between Cambodia and Thailand has collapsed just months after US President Donald Trump claimed to have “ended” their conflict. The Kuala Lumpur Peace Accord, brokered by Washington in August following a five-day war in July, was hailed as a breakthrough. But the deal was built on shaky foundations, on external pressure rather than genuine trust and mutual agreement, and predictably enough, has unravelled.

The agreement required both sides to settle the border dispute peacefully under existing mechanisms, withdraw heavy weapons, clear landmines along the border and release the 18 Cambodian soldiers captured by Thailand one day after the ceasefire in July.

Under the monitoring of the ASEAN Observation Team (AOT), some weaponry was withdrawn, and discussions have been initiated to determine the border areas and release the prisoners. But then in November 2025, a Thai soldier was wounded by a mine along the border. Thailand accused Cambodia of planting fresh mines in its soil. Cambodia insisted the mines were remnants from a former war zone inside its territory.

Days later, Thailand alleged that Cambodia launched shots at its soldiers. Cambodia denied this but Thailand resumed hostilities the next day, vowing to decapacitate its enemy’s army. Ironically, landmines and ‘who-shot-first’ disputes were what triggered the first war in July. Could these triggers have been avoided?

Before the tipping point, Cambodia had complained to AOT about Thailand’s encroachment upon its villages and killing of Cambodian villagers. AOT investigated but delivered no clear findings, leaving any facts and accountability in the vacuum. AOT failed in the same way regarding the landmine incident that led to the current war. The result is several dozen deaths, one million people being displaced, and damage to ancient temples in Cambodia.

AOT is mandated to monitor the peace accord, conduct investigations and enforce compliance. However, this mandate is hamstrung by structural flaws.

First, AOT is under-resourced. With an 800km border to oversee, the team consists of defence attachés from just seven ASEAN states. Under-resourced and reactive, AOT struggles to verify facts or access disputed sites quickly. ASEAN’s non-interference principle further limits its ability to compel compliance, leaving enforcement toothless.

Its inability to investigate incidents swiftly or access disputed sites quickly has left a verification vacuum that has allowed conflicting claims and mistrust to fester.

ASEAN’s principle of non-interference means AOT cannot compel Thailand or Cambodia to comply with border treaties and other bilateral agreements, which limits its ability to enforce findings of any investigations.

Trump intervened again on December 13, calling on both leaders to stop the fighting, later threatening to revoke tariff agreements with the two countries.

Cambodia and Thailand may return to the peace deal under US pressure but phone calls from Washington are unlikely to result in a sustained peace. The role of ASEAN in facilitating confidence-building measures needs to be enhanced.

ASEAN must strengthen its role in confidence-building and equip AOT with resources and authority to act decisively. Swift, credible investigations could defuse tensions before they spiral into war.

The Cambodia-Thailand conflict demonstrates that external pressure from a superpower can force the dispute parties to sign a peace deal but is unlikely to result in a sustained peace.

Sustained peace requires a competent regional body to monitor, investigate and enforce its implementation. This is particularly critical when it involves parties that have a history of failed bilateral mechanisms and deep mutual mistrust where old suspicions will likely reignite, bilateral failures will persist, and fragile peace will remain just that – fragile.