RBK TV,  Russia's business channel, reported recently that Russian President Putin has approved the sale of between two and four S-400 air and missile defense systems to China. If approved, this would make China the first foreign customer of the advanced defense system, which is the most sophisticated in Russia's inventory.  China already deploys a  number of the Soviet-era S-300 defence systems. The RBK TV report was reproduced by BBC Monitoring.