Thailand warned its conflict with neighboring Cambodia could “potentially develop into a war” as troops used rockets and artillery to shell targets along their contested border for a second

"The U.S. already flunked the test and that should be a wakeup call," a former senior U.S. State Department official told Newsweek.

President Donald Trump said Saturday that Cambodia’s prime minister and the acting prime minister of Thailand had agreed to meet immediately

Bangkok and Phnom Penh have been fighting over territory disputed since colonial power France drew the border between them more than a century ago.

Tensions along Cambodia's northern border with Thailand have been simmering since May, when a Cambodian soldier was killed in a clash with Thai forces.

As fighting spread to at least six areas along the arcane frontier, Thailand’s military closed crossings between the countries. The fighting spurred at least 40,000 civilians from more than 80 villages near the border to flee to makeshift bomb shelters of sandbags and car tires.

Thai and Cambodian troops clashed in at least six areas along the countries’ shared 510-mile border on Thursday, killing one Thai soldier and nearly a dozen Thai civilians. The fighting—the second instance of armed confrontation between the two countries in almost two months—has sparked fears that the conflict could escalate into open warfare.

The countries continued to trade fire on Friday, and at least 16 people are reported to have been killed.

China faces a delicate balancing act as it decides what role it should play in the ongoing border hostilities between Thailand and Cambodia, two South-east Asian nations that are its close neighbours and which it wields strong influence over.

Thailand bombed Cambodia with F-16 fighter jets on Thursday, as relations between the two countries imploded following clashes on a disputed border near the Emerald Triangle.

Thailand and Cambodia exchanged heavy artillery fire for a second day on Friday as border fighting intensified and spread, while Cambodia's leader said Thailand had agreed to a Malaysian ceasefire proposal but then backed down.