KUNMING -- On Tuesday, law enforcement officers from China, Laos, Myanmar, and Thailand joined forces to begin the 135th Mekong River joint patrol.

Two Chinese law enforcement vessels left the Guanlei Port in Xishuangbanna Dai autonomous prefecture in Southwest China's Yunnan province at 8 am Tuesday, marking the official start of the joint patrol.

A fleet of seven law enforcement vessels from the four countries was sent to battle various sorts of cross-border crimes in the Mekong River basin and to maintain the region's security and stability.

During the patrol, the joint taskforce from these countries will undertake a search and rescue exercise on the river in Muang Mo, Laos, to learn how to deal with emergencies effectively. Chinese law enforcement will also send a medical team to provide free medical treatment.

The Mekong River, also known as the Lancang River in China, is an important waterway for cross-border transportation. Since December 2011, the four countries have begun conducting cooperative river patrols.