Law enforcement authorities from China, Laos, Myanmar and Thailand held a joint exercise on Wednesday in the Mengmo waters of Laos, 11 kilometers away from the upper reaches of the "Golden Triangle" of the Mekong River, to crack down on illegal activities. The four countries have been conducting joint patrols on the Mekong River since 2011. It is a powerful move to address security challenges and safeguard the environment for development in the Mekong basin.