Receive Breaking News updates as they occur
By Andrew Osborn SEVASTOPOL, Ukraine (Reuters) - Unidentified armed men fired in the air as they moved into a Ukrainian naval post in Crimea on Monday in the latest confrontation since Russian military groups seized control of the Black Sea peninsula. With diplomacy at a standstill, Russia said the United States had spurned an invitation to hold new talks on resolving the crisis, the worst East-West standoff since the Cold War. Ukrainian Prime Minister Arseny Yatseniuk, who said he would address the U.N. Security Council on Thursday, put the blame for the crisis on Russia and accused Moscow of undermining the global security system by taking control of Crimea. Russian forces have in little more than a week taken over military installations across Crimea, home to the Russian Black Sea Fleet and Russian territory until Soviet leader Nikita Khrushchev gave it to Ukraine in 1954.