China, Laos, Burma and Thailand on Sunday began their seventh joint patrol on the Mekong River in the Golden Triangle region, Chinese news agency Xinhua reports. The nations’ police officers will hold a five-day patrol to check ships, passengers and goods for drugs, weapons and stowaways traveling on the river. The joint patrols first started in October 2011 after a gang hijacked two cargo ships and killed 13 Chinese sailors in a Thai-managed part of river. Since the patrols began, the number of Chinese ships using the stretch of the Lower Mekong increased from 10 to 59.