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.

The ceasefire reached in Malaysia was supposed to take effect at midnight on Monday, but it was quickly tested as Thailand and Cambodia continued to accuse each other of violating the truce agreements.