U.S. warns Russia against annexing Crimea --- Having failed to prevent a Russian-sponsored referendum in Crimea, the Obama administration and its European allies refocused their efforts Sunday on keeping Moscow from annexing the autonomous Ukrainian region and expanding its military moves into other parts of Ukraine. -- In a telephone call to Russian President Vladi­mir Putin — his third in two weeks — President Obama said that the referendum “would never be recognized by the United States and the international community” and that “we are prepared to impose additional costs on Russia for its actions,” the White House said. -- An earlier White House statement, issued as Crimean polls were closing on an overwhelming vote by residents to become part of Russia, called Moscow’s actions “dangerous and destabilizing” and said that “military intervention and violation of international law will bring increasing costs for Russia.” -- European Union officials are due to meet Monday to consider measures — including an asset freeze and a travel ban on as-yet-unnamed Russian individuals deemed responsible for military aggression and corruption in Ukraine — that British Foreign Secretary William Hague said “must be adopted.” -- But how far the West is prepared to go in punishing Russia for the referendum, and how much further Putin intends to take his quest for control over part, if not all, of Ukraine, remain uncertain. -- Obama administration promises last week to exact a cost if the vote were held — even before new Russian military exercises on Ukraine’s eastern and southern borders and Saturday’s seizure of a Ukrainian gas plant just beyond Crimea’s northern boundary — would seem to make the imposition of at least some sanctions this week a foregone conclusion. -- The question for the West is whether harsh retribution now will make Putin more or less likely to desist from further action. Although he has so far been impervious to American and European threats, U.S. officials think that the cost the upheaval has already imposed on the Russian economy will become unbearable if Putin does not yield. -- The West could also suffer costs if Russia cuts off energy supplies to Europe and further squeezes the Ukrainian economy. But Western officials say that is a price they are willing to pay and have pledged economic support to Ukraine. - More, Karen DeYoung, Washingtonpost