Russia has called the United States an adversary and told U.S. warships to stay well away from Crimea. It called the deployment of U.S. warships in the Black Sea, a provocation designed to test Russian nerves. According to Russian news agencies, Deputy Foreign Minister Sergei Ryabkov said that the United States is their adversary and does everything it can to undermine Russia's position on the world stage.  Ryabkov's remarks came as two U.S. warships are due to arrive in the Black Sea this week amid an escalation in fighting in eastern Ukraine. Moscow had annexed Crimea from Ukraine in 2014.