Sacred Stones, Shifting Lines

An 11th-century temple and 21st-century nationalism are keeping the Thai–Cambodia border perpetually on edge.

Once again, artillery has spoken along the jungle-clad frontier between Thailand and Cambodia. As fighter jets roar overhead, civilians have fled to makeshift shelters even as a ceasefire signed only weeks ago collapsed with indecent speed. The latest bout of violence, featuring air strikes, casualties and mass displacement, has revived a familiar question in South-East Asia: why does this border, more than a century after it was first drawn, remain so combustible?

The immediate trigger was banal enough. On December 7, a Thai engineering team was working on an access road in a disputed stretch of the frontier when, according to Thailand’s army, Cambodian troops opened fire. Two Thai soldiers were injured, neither of them seriously.

While Cambodia disputes this account, Thailand says multiple positions came under attack and that it was forced to respond. Within hours, the issue escalated as Thai jets struck Cambodian military positions. Bangkok accused Phnom Penh of moving heavy weapons towards the border. Cambodia’s defence ministry countered that Thai forces had launched tank and artillery attacks deep inside its territory, hitting provinces such as Pursat, Banteay Meanchey and Oddar Meanchey.

Villages on both sides of the frontier have emptied while hundreds of families have been displaced. Each capital accuses the other of violating international law as a ceasefire brokered in October now lies in tatters.

Unconventional Conflict

Given that both countries are overwhelmingly Theravada Buddhist, there is no sectarian hatred to inflame passions. Nor is this a conventional resource war. What Thailand and Cambodia are fighting over is heritage in form of a temple laid nearly a millennium ago and a map inked barely a century back.

The roots of the conflict lie in the colonial age. In 1907, when Cambodia was part of French Indochina, Paris and Bangkok produced a map demarcating the border. Thailand disputed parts of it almost immediately. To this day, sections of the frontier remain unmarked, creating grey zones where patrols overlap and tempers fray. The most sensitive of these is the Preah Vihear temple, an 11th-century Hindu sanctuary perched dramatically atop a ridge overlooking the plains.

Both countries have claimed Preah Vihear for decades. In 1962 the International Court of Justice ruled that the temple itself belonged to Cambodia, a judgment Thailand accepted. What the court did not do was clearly demarcate the surrounding land. That omission has proved fateful. While the temple flies the Cambodian flag, the approaches to it remain contested. Troops from both sides have dug in around the site, turning a place of worship into a military tinderbox.

Clashes have erupted there repeatedly, but this year has been particularly bloody. In July, fighting over five days killed 48 people. Alarmed by the prospect of a wider conflict, regional and external powers intervened. A ceasefire was signed in Kuala Lumpur in October after mediation by Malaysia, with the United States lending its weight. Donald Trump, never shy of superlatives, called it a “major breakthrough.” It lasted only weeks.

The Thailand–Cambodia border sits astride a vital Asian trade corridor. Both countries are important American partners. Air strikes between members of ASEAN are almost unheard of; their recurrence now has rattled a region already uneasy about China’s assertiveness and paralysed by Myanmar’s civil war. ASEAN, which prizes consensus and non-interference, looks particularly ill-equipped to manage multiple security crises at once.

At heart, this is a conflict sustained by ambiguity and nationalism. Unclear borders invite patrols; patrols invite incidents; incidents invite politicians to don the mantle of defenders of sovereignty. Domestic politics in both Bangkok and Phnom Penh reward toughness far more than compromise. Each skirmish hardens public opinion, making the next one more likely.

There are remedies, though none are easy. Technical border demarcation, overseen by neutral experts, would remove much of the uncertainty that fuels clashes. ASEAN-led monitoring could lend credibility to ceasefires. Joint economic projects and cultural exchanges around disputed areas might shift the narrative from zero-sum ownership to shared stewardship. Above all, a permanent settlement would deprive nationalists of their favourite grievance.

For now, distrust runs too deep. The rapid collapse of the latest ceasefire shows how fragile existing arrangements are and how readily both sides reach for force.

Until the stones of Preah Vihear are matched by lines on a map that both sides accept, the border will remain a place where history, pride and geopolitics collide and where peace is always provisional.