First came a push from the Malaysian premier, then China reached out, but it was only after President Donald Trump called Thailand's leader last week that Bangkok agreed to talks with Cambodia to end an escalating military conflict.

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.

The fighting between Thailand and Cambodia exposes the depth of global arms proliferation in South-East Asia, proving more sophisticated and deadly than experts expected.