Ceasefire talks between Cambodia and Thailand were underway in Malaysia on Monday after days of deadly clashes on their disputed border sent civilians scrambling for safety and relations between the two neighbors cratering.

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.

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.