Once again the boom of artillery, rockets and air strikes sounds along the Thai-Cambodian border. Villages in a corridor stretching for hundreds of kilometers have been evacuated for a second time in five months. Families and their pets sit on mats in temporary shelters, wondering when they can go home, and when they might be forced to flee yet again.

Why has this happened so soon after the ceasefire brokered by US President Donald Trump in July? It was ignited by a seemingly minor incident on Sunday, when a Thai engineering team working on an access road in the disputed area of the border was, according to the Thai army, fired on by Cambodian troops. Two Thai soldiers were injured, neither seriously.

In the past this might have been settled by some fleet-footed diplomacy. But there has been little of that this year. Instead, a yawning gulf of mistrust lies between these two neighbors, one even Trump’s deal-making prowess has failed to bridge.

Despite his claim to have struck a historic peace deal, the ceasefire he forced on the two countries in July was always tenuous. Thailand in particular was very uneasy about internationalizing the border conflict, and only agreed to the ceasefire because Trump held a tariff gun to its head; at the time both Thailand and Cambodia were just days away from a deadline to negotiate significantly lower tariff rates on their vital exports to the US.

Cambodia, by contrast, welcomed outside intervention. As the smaller country, it feels at a disadvantage in bilateral negotiations with Thailand. However, Cambodian troops have continued to engage in confrontations with the Thai army and have laid new land-mines along the border, causing injuries to Thai soldiers. Thailand has accused Cambodia of bad faith and has refused to release captured soldiers.

Since July, any restraint there was on the Thai armed forces has gone. The current prime minister Anutin Charvirakul has given the military carte blanche to manage the border conflict as it sees fit. The army's goal is to inflict sufficient damage on its Cambodian counterpart to ensure it can never again threaten border communities.

On the Cambodian side, motivations are complex, as former Prime Minister Hun Sen continues to exert significant influence. He portrays Cambodia as being bullied by a more powerful neighbor, appealing for international support. However, his decisive interventions this year have escalated tensions, particularly after a leaked phone call with then-Thai PM Paetongtarn Shinawatra.

With public sentiment in favor of a hardline approach in Thailand, there is skepticism about future diplomatic efforts. As cries for peace echo again, the potential for another ceasefire remains uncertain, with both nations needing to address their grievances and establish trust before negotiations can resume.