Thailand-Cambodia conflict intensifies, spreads along disputed border

Renewed fighting along the Thailand–Cambodia border intensified on Tuesday, as Thailand said its forces were taking action to expel Cambodian troops detected inside Thai territory. 

The escalation marks the latest flare-up along the longstanding disputed frontier. Each side has blamed the other for the clashes, which have derailed a fragile ceasefire brokered by U.S. President Donald Trump that ended five days of fighting in July.

Cambodia's Defense Ministry said on Tuesday morning that Thai military carried out unending shooting throughout the night in Geography of Military Village Part 5, and two civilians had been killed overnight, taking its death toll to six. One Thai soldier has died in the fighting.

The Thai Navy said in a statement that Cambodian forces had been detected inside Thai territory in the coastal province of Trat and military operations were launched to expel them, without providing further details.

Cambodian Prime Minister Hun Manet said late on Monday that Thailand "must not use military force to attack civilian villages under the pretext of reclaiming its sovereignty".

Earlier, Cambodia said it had not retaliated even after its forces came under sustained attack.

The Thai Navy said Cambodian forces were increasing their presence, deploying snipers and heavy weapons, improving fortified positions and digging trenches, adding it saw the actions "as a direct and serious threat to Thailand's sovereignty".

Monday's clashes were the fiercest since a five-day exchange of rockets and heavy artillery in July, when at least 48 people were killed and 300,000 displaced, before Trump intervened to broker a ceasefire.

Thailand evacuated 438,000 civilians across five border provinces and the Cambodian authorities said hundreds of thousands of people had been moved to safety. Thailand's army said 18 soldiers were wounded and Cambodia's government reported nine civilians injured.

Thailand and Cambodia have for more than a century contested sovereignty at undemarcated points along their 817-kilometer land border, with disputes over ancient temples and occasional armed flare-ups, including a deadly week-long artillery exchange in 2011.

The latest tensions rose in May following the killing of a Cambodian soldier during a skirmish, which led to a major troop buildup at the border and escalated into diplomatic breakdowns and armed clashes. On October 26, during the ASEAN summit held in Malaysia, the two countries signed a joint peace declaration, after which both sides began withdrawing heavy weapons from the border.

Malaysian Prime Minister Anwar Ibrahim said on Monday that the renewed fighting risks unraveling the careful work that has gone into stabilizing relations between the two neighbors.

"Our region cannot afford to see long-standing disputes slip into cycles of confrontation. The immediate priority is to halt the fighting, safeguard civilians and return to a diplomatic path supported by international law and the neighborly spirit on which ASEAN depends," Anwar said.

Ong Tee Keat, a former Malaysian transport minister, noted that the Thailand-Cambodia border dispute has deep historical roots. Relying solely on U.S. pressure through trade agreements, without addressing core issues, offers only a temporary fix and makes any ceasefire hard to sustain, he said.

Both countries need mediators who are trusted by both sides, he added.

(With input from agencies)