Drones, the unmanned aircraft that can spy and kill, are most associated with US President Barack Obama's administration, which has used them extensively in its fight against terrorists, staking out and claiming targets in Pakistan, Somalia and Yemen. So versatile and successful have they been that there is burgeoning demand among other governments to acquire or develop them. Unsurprisingly, there is a growing desire to use them in the same questionably legal ways. China contemplated using a drone strike on foreign soil to kill a drug warlord from Myanmar wanted for the brutal murders of 13 Chinese sailors on the Mekong River in 2011. Revealed in the state media last month by a public security official, the plan would have involved bombing the hideout of Naw Kham in Myanmar's mountainous Shan state. The idea was eventually shelved and the suspect was arrested by Laotian authorities after a six-month hunt. Whether China's drone and satellite technology is advanced enough for such a mission is unclear, but its mere mention has drawn attention to the implications and spread of armed unmanned aircraft. Such vehicles are no longer the sole domain of the US and the two other long-time producers, Britain and Israel. Now in the hands of dozens of countries, they are mostly used for surveillance, but can easily be converted to carry missiles and guns. China has vastly improved its technology and unveiled a wide range of models, many increasingly affordable for governments and organisations. Despite the prevalence of drones and their ability to slip across national boundaries, there are no international rules governing their use. The US has led the way, seemingly adopting a principle of having the right to kill anyone, anywhere, any time, by any means. Its justification is that it is at war with terrorists, but there are doubts as to whether a war is under way and a lack of transparency as to the criteria. Setting such a poor example raises concerns about drones falling into the hands of irresponsible people. China's military opaqueness and its need to protect far-flung interests have raised fears among neighbours and rivals; last week's report heightened worries. Demand and proliferation necessitate urgent action. Obama's administration has to take the lead, being more specific about drone use and putting in place regulation through the judicial system. The international discussion has to be elevated so that sturdy rules can be agreed upon.