Cambodia’s Senate President Hun Sen vowed Tuesday that his country would mount a fierce fight against Thailand as renewed clashes along the border forced tens of thousands to flee.

The fighting erupted after a skirmish Sunday night in which a Thai soldier was killed, despite a July cease-fire that had ended five days of combat over contested border territory—a conflict that previously claimed dozens of civilian and military lives and displaced more than 100,000 people.

In a statement on Facebook and Telegram, Hun Sen said Cambodia had held fire Monday but began returning fire overnight, focusing on areas of Thai advance to “weaken and destroy enemy forces through counterattacks.”

Thailand’s army reported that Cambodian forces fired artillery at a village in Sa Kaeo province early Tuesday, causing no casualties. Both sides continue to blame each other for initiating the latest clashes.

A Thai army's self-propelled howitzer moves during clashes between Thai and Cambodian troops in Phanom Dong Rak district, Surin province, Thailand, Dec. 9, 2025. (EPA Photo)