Decades-old competing territorial claims and unresolved boundary demarcation have underpinned renewed border tensions between Thailand and Cambodia, culminating in some of the most severe clashes between the neighbouring Southeast Asian states in recent memory.

The immediate flashpoints lie along contested frontier areas where historical treaties, colonial maps and interpretations of sovereignty intersect, particularly near ancient temple sites that both Bangkok and Phnom Penh have long claimed as symbols of national heritage and territory.

The frontier’s instability reflects deep-rooted disagreements over the precise delineation of land borders first negotiated under colonial-era agreements and later shaped by intermittent technical negotiations that have repeatedly stalled.

The International Court of Justice in the Sixties and later decisions awarded specific sites to Cambodia, but surrounding tracts of land have remained disputed and poorly demarcated, providing recurring triggers for military confrontations.

Modern tensions escalated sharply in twenty-twenty-five when a fragile ceasefire between the two governments collapsed, leading to sustained armed engagement that involved artillery exchanges, aircraft operations and frontier skirmishes that resulted in significant casualties and displacement of civilians from both sides.

The conflict displaced tens of thousands of people and led to humanitarian concerns across border communities.

While recent diplomatic efforts — including a new ceasefire and prisoner releases — have eased immediate hostilities, the underlying causes persist.

These include differing interpretations of historical treaties, ambiguous boundary markers, and domestic political pressures that have made compromise difficult.

Broader geopolitical dynamics have also shaped the dispute, as regional powers and external actors have engaged with both capitals, adding layers of diplomatic complexity to a conflict rooted in centuries of contested borders.

Technical mechanisms such as the Joint Boundary Commission have periodically been invoked to chart a mutually acceptable border, but progress has been slow.

As both Thailand and Cambodia seek to stabilise relations, analysts warn that sustainable peace will require renewed commitment to demarcation talks, legal clarity on territorial limits, and confidence-building measures that reduce the likelihood of future outbreaks of violence along one of Southeast Asia’s most sensitive land frontiers.