Cambodia–Thailand Conflict: Borders Should Not Be Battlefields

The armed confrontation between Cambodia and Thailand from 24 to 28 July 2025 was the latest flare-up in a dispute rooted in history, contested legal interpretations, and nationalist politics. A purely military or unilateral approach will only perpetuate cycles of provocation, militarisation, and sporadic clashes, damaging ASEAN unity and the international reputations of both countries. The two sides need a multi-pronged approach based on cooperation and trust.

The bilateral dispute is longstanding and unresolved. While the 1904 and 1907 Franco–Siam treaties and the maps produced by the Franco–Siamese Commission placed sites such as the Preah Vihear, Tamoan Thom, Tamoan Touch, and Ta Krobei temples within Cambodian territory, the border remains incompletely demarcated. This leaves areas vulnerable to competing claims and the occasional flare-up.

The dispute is also shaped by domestic politics. In 2008, when Cambodia sought UNESCO World Heritage status for Preah Vihear, Thailand initially signalled support, on the condition that this would not prejudice outstanding border demarcations. However, political turmoil in Bangkok soon turned the issue into a nationalist rallying cry. From 2008 to 2011, repeated skirmishes along the frontier caused casualties on both sides. Although the International Court of Justice (ICJ) affirmed Cambodia’s sovereignty over Preah Vihear in 1962 and again in 2013, adjacent areas remain contested, allowing tensions to resurface periodically.

On 28 May, a Cambodian soldier was killed in a clash with Thai troops in Preah Vihear’s Mom Bei area. The incident came in the wake of months of rising tensions. Cambodia claims that Thai forces launched an unprovoked attack, while Thailand insists it acted in self-defence, with both sides blaming the other for firing first. Thailand rejected Cambodia’s call for an impartial third-party investigation, leading to significant troop buildup on both sides. Inflammatory remarks, such as General Boonsin Padklang’s pre-28 July threat to capture Phnom Penh within three days, further escalated tensions and violated principles of good neighbourliness, peace and regional harmony. Combined with rising nationalist sentiment, often stoked by reckless statements, such rhetoric risks sparking ethnic divisions and undermining bilateral stability.

It must be acknowledged that tensions persist partly because both sides have at times allowed domestic politics to affect diplomacy. In Thailand, political volatility, the influence of the military, and periodic surges in nationalist sentiment have incentivised hardline stances. In Cambodia, while the government has consistently relied on legal arguments and international adjudication, it has sometimes struggled to engage Thailand politically when Bangkok’s domestic conditions were unfavourable. Successive Cambodian governments have often used foreign policy, particularly disputes with Thailand over the Preah Vihear temple in 2008-2011, as a way to reinforce domestic political narratives of sovereignty and national pride.

Cambodia has always chosen the path of dialogue, patience, and strict adherence to international law. The kingdom’s advocacy for peaceful settlement is driven by a commitment to mutual respect, stability, and the belief that good neighbours resolve differences without resorting to arms. Cambodia has avoided escalation even in the face of provocation, fully aware that armed conflict endangers soldiers and civilians alike.

For lasting peace, both governments must commit to respecting treaties, ICJ rulings, and the principle of non-use of force. This requires political courage, especially in resisting domestic pressure to take provocative stances.

Nonetheless, the gravity of the current situation compels decisive action to safeguard Cambodia’s sovereignty and protect the people. On 15 June, Cambodia formally notified the ICJ of its intention to seek adjudication on these unresolved disputes involving the four contested sites. After the 28 July ceasefire agreement, Malaysia, as the 2025 ASEAN Chair, led the formation of an interim observer team composed of military attachés from seven ASEAN member states — Indonesia, Malaysia, Laos, Myanmar, the Philippines, Singapore, and Vietnam — to monitor compliance with the ceasefire agreement. This team was deployed to conflict-affected areas in Cambodia’s Oddar Meanchey and Preah Vihear provinces starting on 3 August. Despite these peaceful initiatives, General Boonsin pledged again on 10 August that Thailand would seize Ta Krobei and vowed not to allow Cambodian tourists to visit the temple. Such a statement was seen as a provocative and aggressive threat that violated the spirit, if not the letter, of the ceasefire agreement.

Importantly, Cambodia has neither the economic strength nor the military capacity to match Thailand in an armed confrontation. Cambodia’s GDP is roughly one-fifth of Thailand’s, and its military budget is significantly smaller (US$1.3 billion versus Thailand’s US$5.7 billion). The Royal Cambodian Armed Forces are structured primarily for national defence, not prolonged cross-border combat. This reality underpins Phnom Penh’s strategy of restraint: avoiding escalation, prioritising legal avenues, and working through ASEAN and international mechanisms. Cambodia’s leadership understands that an armed conflict would not only risk heavy casualties but also undermine economic growth and investor confidence.

The two countries also share deep cultural, historical, and economic ties that should form the basis for reconciliation.

Cambodia’s 15 June request for ICJ adjudication over four disputed sites is not an act of hostility, but a reaffirmation of peaceful dispute settlement under the UN Charter. The presence of ASEAN observers in both countries since 3 August provides a rare opportunity to de-escalate tensions and prevent further violence.

Both sides need to adopt a multifaceted approach built on cooperation and mutual trust. First, they should accelerate the completion of joint border demarcation in line with international law and ICJ judgments, with technical assistance from impartial third parties to guarantee credibility.

Second, disputed zones should be gradually demilitarised. This entails the withdrawal of troops and replacing them with joint or neutral monitoring teams to reduce the risk of accidental clashes. The interim ASEAN observer team deployed in August 2025 should be developed into a permanent mechanism to ensure compliance with ceasefire agreements and provide confidence-building measures.

Third, cultural heritage should be depoliticised by removing heritage sites from domestic political agendas and promoting them jointly as symbols of cooperation and shared history. Cambodia and Thailand should strengthen cooperation in border trade and economic integration, enhance joint security efforts, expand tourism linkages, and improve labour mobility and protection.

Finally, establishing direct crisis communication channels, such as a hotline between military commanders, is essential to defuse incidents quickly and prevent escalation into broader conflict.

For lasting peace, both governments should commit to respecting treaties, ICJ rulings, and the principle of non-use of force. This requires political courage, especially in resisting domestic pressure to take provocative stances.

Borders should not be battlefields but bridges of cooperation. Turning this vision into reality will demand not only legal clarity but also sustained political will, mutual trust, and a shared commitment to regional stability.

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