SURIN, Thailand -- Three Thai civilians were killed as heavy combat continued along the country's border with Cambodia, the Thai military said Thursday, marking the country's first civilian fatalities since the fighting resumed.

Armed clashes between Thailand and Cambodia entered a second day on Tuesday, both sides said, in defiance of calls from the United States to stop fighting and adhere to a months-old Trump-brokered peace deal that now looks on the brink of complete collapse.

Cambodia said Thailand launched more airstrikes Thursday, as heavy fighting flared along the two countries' border and both sides accused the other of violating their sovereignty along the contested border region.

A resurgence of violence along the Thai-Cambodia border, including Thai airstrikes on targets in Cambodia on Monday, comes less than two months after the signing of a peace agreement between the countries that was championed by President Donald Trump as part of a global effort to secure peace deals and secure his reputation as a peacemaker.