A Thai soldier stands guard at Ban Kaen Kai operation base on the Mekong river at the border between Thailand and Laos March 3, 2016. Patrols on the Mekong River by the Laotian army and Myanmar police have subdued pirates who once robbed cargo ships with impunity. But drug production and trafficking in the region, known as the Golden Triangle, is booming - despite the presence of Chinese gunboats and Chinese armed police. The United Nations Office on Drugs and Crime estimates that Southeast Asia's trade in heroin and methamphetamine was worth $31 billion in 2013. REUTERS/Jorge Silva SEARCH "SILVA MEKONG" FOR THIS STORY. SEARCH "THE WIDER IMAGE" FOR ALL STORIES