Former Russian president Dmitry Medvedev has become embroiled in a tense back-and-forth on social media that prompted U.S. President Donald Trump to announce he had ordered the re-positioning of two U.

Russia and China are staging mock combat drills and other war games in the Sea of Japan in a sign of strengthening military ties.

Former Russian president Dmitry Medvedev, who is currently serving as deputy chair of the security council of the Russian Federation, is embroiled in a social media spat with United States President Donald Trump,