MOSCOW (Reuters) -Former Russian President Dmitry Medvedev on Thursday told U.S. President Donald Trump to remember that Moscow possessed Soviet-era nuclear strike capabilities of last resort after Trump told Medvedev to "watch his words". Trump, in a post on his Truth social network in the early hours of Thursday, singled out Medvedev, who is deputy chairman of Russia's Security Council, for sharp criticism after Medvedev said that Trump's threat of hitting Russia and buyers of its oil with punitive tariffs was "a game of ultimatums" and a step closer towards a war between Russia and the United States.