Tensions between Thailand and Cambodia have surged once again after a series of lethal exchanges along their heavily militarized border, undermining a ceasefire mediated earlier this year with U.S. involvement. The renewed violence, which has killed soldiers and civilians on both sides, stems from long-standing disagreements over historic boundary lines and the administration of contested land surrounding an ancient temple complex.

Border Dispute Rekindles Decades of Tension

The two neighbours’ territorial dispute dates back more than a hundred years, to the mapping of borders after France’s occupation of Cambodia. Pressure intensified in 2008 when Cambodia sought UNESCO World Heritage status for an 11th-century temple in the contested zone — a move that provoked anger in Thailand and ignited sporadic clashes that continued over the next decade.

Rising Strains in 2024 Set the Stage for December Violence

Relations deteriorated further this year after a Cambodian soldier was killed in May, prompting both sides to impose border restrictions. Cambodia banned the import of Thai produce, electricity and internet services, while both armies increased troop concentrations along the frontier. These steps laid the groundwork for renewed escalation in December.

December’s Escalation

On 8 December, Thai forces reported that Cambodian units opened fire in Ubon Ratchathani province, killing a Thai soldier and triggering Thai airstrikes on military targets. Cambodia disputed this version, insisting Thailand initiated the exchange and that Cambodian troops did not retaliate.

Drone Strikes, Rockets and Civilian Casualties Reported

A day later, Thailand accused Cambodia of using rockets, explosive-dropping drones and “kamikaze” UAVs against Thai troops — some landing in civilian areas. Cambodia countered with its own allegations, claiming Thai forces indiscriminately shelled populated districts across the border.

What Happened During the July Clashes?

Violence earlier in July spiralled rapidly after both sides blamed each other for opening fire. Thailand accused Cambodia of launching rockets, then responded with airstrikes on Cambodian military positions. The five-day confrontation left at least 48 people dead and displaced thousands.

Trump’s Mediation Produced a Ceasefire — Temporarily

The U.S. intervened following the July escalation, with U.S. President Donald Trump brokering a ceasefire alongside Malaysia. The deal — dubbed the “Kuala Lumpur Peace Agreement” by Washington — was signed in October, though Thailand rejected the label and referred to it merely as a “joint statement.” Both sides pledged to withdraw heavy weapons and establish a temporary monitoring force.

Collapse of the Ceasefire

In November, Thailand announced it was suspending the arrangement, arguing that security risks “had not genuinely diminished.” Cambodia insisted it remained fully committed. Following the December clashes, Thailand’s foreign minister declared the ceasefire “ineffective,” while former Cambodian prime minister Hun Sen said his country returned fire only in self-defense.

U.S. Calls for Restraint Amid Uncertain Outlook

Trump urged both countries to respect their commitments, but analysts warn that neither Bangkok nor Phnom Penh currently has leadership with the political capital — or trust — required to de-escalate the situation. Past flare-ups have been contained relatively quickly, but experts say the present climate is notably more fragile.