Moscow urged restraint in the Korean peninsular on Saturday, after North Korea said it was entering a "state of war" with South Korea in a further escalation of its bellicose rhetoric against Seoul and its main ally, the United States. "We hope that all parties will exercise maximum responsibility and restraint and no-one will cross the point of no return," senior Russian Foreign Ministry official Grigory Logvinov told Interfax news agency. North Korean leader Kim Jong-un on Friday put missile units on standby to attack U.S. military bases in the South and the Pacific, after two nuclear-capable U.S. stealth bombers flew over the Korean peninsula in a rare show of force. Russia warned on Friday that the heightened military activity was slipping into a "vicious cycle" that could get out of control. Tension has been high since North Korea conducted a third nuclear weapons test in February in breach of U.N. sanctions and despite warnings from China for it not to do so.