A threat by President Donald Trump to halt trade negotiations with both Cambodia and Thailand until a truce had been reached forced both sides to the negotiating table. Even so, the ceasefire looks shaky.

Long-simmering tensions between Thailand and Cambodia escalated to deadly violence on July 24, setting off five days of military clashes at multiple spots along the roughly 800-kilometer (500 mile) border.

Intense nationalism and disputed history — and maps — stoke the neighbors’ hostilities. Even a surge of international diplomacy has brought little hope of a lasting peace.