Ukraine's Prime Minister Yatseniuk welcomes OSCE observers inside a plane upon their arrival at Boryspil International airport outside Kiev
Ukraine's Prime Minister Arseny Yatseniuk (L) welcomes OSCE observers inside a plane upon their arrival at Boryspil International airport outside Kiev May 3, 2014. A group of military observers who were seized last week by pro-Russian separatists in the eastern Ukrainian city of Slaviansk has been released, the Organization for Security and Cooperation in Europe (OSCE) confirmed on Saturday. REUTERS/Andrew Kravchenko/Pool (UKRAINE - Tags: POLITICS CIVIL UNREST TRANSPORT)
OSCE observers walk downstairs upon their arrival at Boryspil International airport outside Kiev
OSCE observers walk downstairs upon their arrival at Boryspil International airport outside Kiev May 3, 2014. A group of military observers who were seized last week by pro-Russian separatists in the eastern Ukrainian city of Slaviansk has been released, the Organization for Security and Cooperation in Europe (OSCE) confirmed on Saturday. REUTERS/Andrew Kravchenko/Pool (UKRAINE - Tags: POLITICS CIVIL UNREST TRANSPORT)
Local residents attend a rally as members of the Ukrainian Interior Ministry security forces stand guard outside a trade union building in Odessa
Local residents attend a rally as members of the Ukrainian Interior Ministry security forces stand guard outside a trade union building in Odessa, May 3, 2014. At least 42 people were killed in street battles between supporters and opponents of Russia in southern Ukraine that ended with pro-Russian protesters trapped in a flaming building, bringing the country closer to war. The riot in the Black Sea port of Odessa that ended in a deadly blaze in a trade union building was by far the worst incident in Ukraine since a February uprising that ended with a pro-Russian president fleeing the country. REUTERS/Gleb Garanich (UKRAINE - Tags: POLITICS CIVIL UNREST CRIME LAW)
Man, wearing a black and orange ribbon of St. George, reacts outside trade union building, where a deadly fire occurred, with members from the Ukrainian Interior Ministry security forces seen in the background, in Odessa
A man, wearing a black and orange ribbon of St. George, a symbol widely associated with pro-Russian protests in Ukraine, reacts outside a trade union building, where a deadly fire occurred, with members from the Ukrainian Interior Ministry security forces seen in the background, in Odessa, May 3, 2014. At least 42 people were killed in street battles between supporters and opponents of Russia in southern Ukraine that ended with pro-Russian protesters trapped in a flaming building, bringing the country closer to war. The riot in the Black Sea port of Odessa that ended in a deadly blaze in a trade union building was by far the worst incident in Ukraine since a February uprising that ended with a pro-Russian president fleeing the country. REUTERS/Gleb Garanich (UKRAINE - Tags: POLITICS CIVIL UNREST CRIME LAW TPX IMAGES OF THE DAY)
Pro-Russia protesters storm the governor's business premises in Donetsk, eastern Ukraine
Pro-Russia protesters storm the governor's business premises in Donetsk, eastern Ukraine May 3, 2014. A couple of hundred pro-Russian protesters in the eastern city of Donetsk stormed the governor's business premises and the state security headquarters, ransacking files and smashing windows. The attack reflected growing disorder in the area, targeting as it did a security building that was already largely under rebel control. REUTERS/Marko Djurica (UKRAINE - Tags: POLITICS CIVIL UNREST)
Members from the Ukrainian Interior Ministry security forces stand guard outside a trade union building in Odessa
Members from the Ukrainian Interior Ministry security forces stand guard outside a trade union building in Odessa, May 3, 2014. At least 42 people were killed in street battles between supporters and opponents of Russia in southern Ukraine that ended with pro-Russian protesters trapped in a flaming building, bringing the country closer to war. The riot in the Black Sea port of Odessa that ended in a deadly blaze in a trade union building was by far the worst incident in Ukraine since a February uprising that ended with a pro-Russian president fleeing the country. REUTERS/Gleb Garanich (UKRAINE - Tags: POLITICS CIVIL UNREST CRIME LAW)
A pro-Russia protester breaks a window at the governor's business premises in Donetsk, eastern Ukraine
A pro-Russia protester breaks a window at the governor's business premises in Donetsk, eastern Ukraine May 3, 2014. A couple of hundred pro-Russian protesters in the eastern city of Donetsk stormed the governor's business premises and the state security headquarters, ransacking files and smashing windows. The attack reflected growing disorder in the area, targeting as it did a security building that was already largely under rebel control. REUTERS/Marko Djurica (UKRAINE - Tags: POLITICS CIVIL UNREST)
A pro-Russia protester sprays champagne as they storm the governor's business premises in Donetsk, eastern Ukraine
A pro-Russia protester sprays champagne as they storm the governor's business premises in Donetsk, eastern Ukraine May 3, 2014. A couple of hundred pro-Russian protesters in the eastern city of Donetsk stormed the governor's business premises and the state security headquarters, ransacking files and smashing windows. The attack reflected growing disorder in the area, targeting as it did a security building that was already largely under rebel control. REUTERS/Marko Djurica (UKRAINE - Tags: POLITICS CIVIL UNREST)
Ukrainian Interior Ministry security forces members stand guard outside a trade union building in Odessa
Ukrainian Interior Ministry security forces members stand guard outside a trade union building in Odessa, May 3, 2014. At least 42 people were killed in street battles between supporters and opponents of Russia in southern Ukraine that ended with pro-Russian protesters trapped in a flaming building, bringing the country closer to war. The riot in the Black Sea port of Odessa that ended in a deadly blaze in a trade union building was by far the worst incident in Ukraine since a February uprising that ended with a pro-Russian president fleeing the country. REUTERS/Gleb Garanich (UKRAINE - Tags: POLITICS CIVIL UNREST CRIME LAW)
A woman holds a sign outside town administration building in Kramatorsk, eastern Ukraine
A woman holds a banner outside a town administration building in Kramatorsk, eastern Ukraine May 3, 2014. Ukrainian forces have retaken the security service headquarters in the eastern town of Kramatorsk, south of rebel stronghold Slaviansk, the country's Interior Ministry said on Saturday. The sign reads "The Kiev junta carries out the U.S. scenario". REUTERS/Marko Djurica (UKRAINE - Tags: POLITICS CIVIL UNREST)