Hun Sen is a wily survivor of Cambodian politics and the wider tumult across Southeast Asia over the last half-a-century. Born to rice farmers in a province heavily bombed during the secret U.S. war in Cambodia and Laos, he became a soldier for the Khmer Rouge, whose murderous regime from 1975 to 1979 killed about a quarter of the population.

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.

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.