Masked pro-Russian activists rise their flag on top of a government building in Donetsk, eastern Ukraine
Masked pro-Russian activists rise their flag on top of a government building in Donetsk, eastern Ukraine April 28, 2014. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
Masked pro-Russian activists remove the Ukrainian flag from the top of a government building in Donetsk
Masked pro-Russian activists remove the Ukrainian flag from the top of a government building in Donetsk, eastern Ukraine April 28, 2014. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
Ukrainian police stand guard in front of masked pro-Russian activists at a government building in Donetsk
Ukrainian police stand guard in front of masked pro-Russian activists at a government building in Donetsk, eastern Ukraine April 28, 2014. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
Pro-Russian activists protest at the Privat Bank in Donetsk, eastern Ukraine
Pro-Russian activists protest at the Privat Bank in Donetsk, eastern Ukraine April 28, 2014. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
A pro-Russian activist hangs the Donetsk flag during a protest at the Privat Bank in Donetsk, eastern Ukraine
A pro-Russian activist hangs the Donetsk flag during a protest at the Privat Bank in Donetsk, eastern Ukraine April 28, 2014. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
Russia's Volga Group says U.S. sanctions "politically motivated"
UKRAINE-CRISIS/RUSSIA-VOLGA GROUP (URGENT):Russia's Volga Group says U.S. sanctions "politically motivated"
Masked pro-Russian activists throw away a Ukrainian flag after taking it down from the top of a government building in Donetsk
Masked pro-Russian activists throw away a Ukrainian flag after taking it down from the top of a government building in Donetsk, eastern Ukraine April 28, 2014. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
File photo of Gennady Kernes, the pro-Russian mayor of Kharkiv
Gennady Kernes, the pro-Russian mayor of Kharkiv, is seen in Kharkiv in this August 5, 2010 file photo. Kernes was in a serious condition on April 28, 2014 after being shot in the back while riding his bicycle, the latest violence in the country's east. REUTERS/Stringer/Files (UKRAINE - Tags: CIVIL UNREST POLITICS HEADSHOT)
Masked pro-Russian activist takes down a Ukrainian flag from the top of a government building in Donetsk
A masked pro-Russian activist takes down a Ukrainian flag from the top of a government building in Donetsk, eastern Ukraine April 28, 2014. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
Mask pro-Russian activists carry a flag to the top of a government building in Donetsk
Mask pro-Russian activists carry a flag to the top of a government building in Donetsk, eastern Ukraine April 28, 2014. REUTERS/Baz Ratner(UKRAINE - Tags: POLITICS CIVIL UNREST)