U.S. Vice President Joe Biden has warned that the United States could impose tougher sanctions on Russia if it undermines Ukraine's presidential elections on May 25.
Biden Warns Russia of Tougher Sanctions if Ukraine Polls Undermined

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Local residents walk with their young children in a park, in Donetsk, May 21, 2014.

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Workers stand near pipes at a gas compressor station near Uzhhorod. Russia has said state-controlled exporter Gazprom will not supply Ukraine with gas in June if Kyiv fails to pay in advance, May 21, 2014.