The latest flare-up started on Thursday, with intense fighting spreading across multiple border areas. Early Saturday, Thailand’s navy joined the army in repelling what it described as incursions by Cambodian troops at three points in eastern Trat province.

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

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.

Thailand and Cambodia clashed for a fourth day on Sunday, despite US President Donald Trump warning them they are risking potential trade deals with the US. The US president said on Saturday the leaders of the two countries had agreed to meet to negotiate a ceasefire.

The conflict over the shared border between the two countries grew on Saturday, in the deadliest conflict between them in more than a decade.

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 leaders of Cambodia and Thailand have agreed to meet to negotiate a ceasefire, according to a social media post by United States President Donald Trump on Saturday.

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

Thailand has rejected mediation efforts from third countries to end the ongoing conflict with Cambodia, insisting that Phnom Penh cease attacks and resolve the situation only through bilateral talks,

Cambodia and Thailand exchanged fire across their disputed border for a fourth day on Sunday, hours after US President Donald Trump announced the two Southeast Asian nations had agreed to ceasefire talks and threatened continued fighting would jeopardize their trade deals with Washington.