Thailand and Cambodia shut several border crossings in tit-for-tat moves, ratcheting up tensions between the two Southeast Asian neighbors as Prime Minister Paetongtarn Shinawatra fights to save her government from a political crisis triggered by a leaked phone call over the weekslong standoff.

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.

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.