REPUBLIKA.CO.ID, KIEV - An east-west struggle over Ukraine turned nastier as Moscow accused the United States of fomenting a coup and Washington pointed a finger at Russia for leaking a recording of US  diplomats discussing how to shape a new government in Kiev.

As Russian President Vladimir Putin prepared to open the Winter Olympics at Sochi, the first Games in Russia since the Soviet Union hosted the 1980 summer edition, the showdown over Ukraine produced chilly Cold War rhetoric, with a Kremlin aide warning Moscow might act to block US "interference" in Kiev.

US-Russian relations have long been far from warm and there seems little chance yet of conflict going much beyond verbal sparring, but the ferocity of the exchanges was a mark of the importance of Ukraine, a sprawling former Soviet state of 46 million people that Putin wants to keep in Moscow's economic orbit.

Putin is likely to meet the Ukrainian president in Sochi, possibly to discuss Viktor Yanukovich's plans for a new prime minister - plans on which billions in Russian aid depend. He may also raise concerns, voiced by the Kremlin's point man on Ukraine, that Yanukovich needs to crack down on protesters who have been on the streets for over two months, demanding he quit.