Police officers protect a wounded participant of an anti-war rally during clashes with pro-Russian demonstrators in Donetsk March 9, 2014. Russian forces tightened their grip on Crimea on Sunday despite a U.S. warning to Moscow that annexing the southern Ukrainian region would close the door to diplomacy in a tense East-West standoff. REUTERS/Konstantin Chernichkin (UKRAINE - Tags: POLITICS CIVIL UNREST)