China Claims EM Drive In Development
Dr. Chen Yue, Director of Commercial Satellite Technology for the China Academy of Space Technology (CAST) announced on December 10, 2016 that China has successfully tested EM Drives in its laboratories, and that their proof-of-concept is currently undergoing further testing in a zero-g environment. According to the International Business Times, this testing is taking place on their Tiangong 2 space station.
An EM drive is a "reactionless" engine propelled solely by electromagnetic radiation confined in a microwave cavity. Such an engine seemingly violates the law of conservation of momentum by generating mechanical action without exchanging matter. Since 2010, both the US and China have been seriously interested in developing the concept, but it appears as though China may be the first nation to do so.
Source: Popular Science