A fuel shortage in Cambodia has triggered a surge of cross-border traffic into Thailand, as Cambodian motorists flock to fill their tanks with cheaper and more readily available fuel.

The reescalation of conflict was sparked on May 28, when a Cambodian soldier was killed in an early morning clash between both nations’ troops, in an area called the Emerald Triangle—the shared border between Thailand, Cambodia, and Laos. The area remains disputed as both Thailand and Cambodia lay claims to parts of the region.

Tens of thousands of people gathered in Cambodia’s capital Phnom Penh on Wednesday for a march to show their solidarity with the government and military, amid soaring tensions with neighboring Thailand following a border row that erupted last month.