Renewed hostilities between Thailand and Cambodia are a wake-up call for Southeast Asia about the costs of letting historical border disputes fester. The century-old conflict, rooted in colonial-era cartography, is flaring at a moment when the region is already under strain from President Donald Trump¡¯s trade war and intensifying great-power rivalry between the U.S. and China.

Fighting erupted nearly a week ago along their shared frontier, killing nearly a dozen people. Both sides have exchanged artillery fire and Thailand carried out air strikes with F-16 jets after accusing Cambodia of firing rockets into civilian areas.

The neighbors have clashed repeatedly before, most recently in July, when dozens were killed and tens of thousands displaced. A fragile ceasefire ¡ª brokered in part with Trump¡¯s self-touted involvement ¡ª has collapsed and there is no clear diplomatic off-ramp in sight.