China has begun joint patrols on the Mekong River with three other countries in the region to enhance security, after a series of attacks.Joint patrols with Burma and Laos started on Saturday morning, China\'s state media reported.Personnel from Thailand are expected to join the operation further downstream, possibly on Sunday.The patrols are a response to the killing of 13 Chinese sailors travelling on the river in October.The four-nation deployment aims to fill a security vacuum in the Golden Triangle region, an area notorious for drug-trafficking.China\'s booming trade along the Mekong was suspended after the attack on 5 October left the bodies of the Chinese crew members floating in the water.Drug smugglers were initially suspected of the attack, but nine Thai soldiers were subsequently detained.More than 200 police from the border defence force in Yunnan province will take part, China\'s public security ministry said on Friday.It is not yet clear how they will link up with their Burmese, Lao and Thai counterparts, how far along the Mekong the patrols will go, or if officers from one country will be able to perform arrests in others\' territorial waters.China\'s declared policy of non-interference in other countries\' affairs has shifted as its economic horizons expand.The Chinese navy has played a prominent role in the international operation off Somalia, protecting shipping from pirate attack.But this is the first such joint deployment in South East Asia, where China\'s growing assertiveness is being watched closely.