A Ukrainian soldier stands guard near an armoured personnel carrier at a checkpoint near the town of Slaviansk in eastern Ukraine
A Ukrainian soldier stands guard near an armoured personnel carrier at a checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. Pro-Russian rebels shot down two Ukrainian helicopters on Friday, killing two crew, as troops tightened their siege of separatist-held Slaviansk and Moscow accused Kiev of launching a "criminal" assault that wrecked hopes of peace. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST MILITARY)
A civilian holds a sign in front of Ukrainian troops at a checkpoint near the town of Slaviansk in eastern Ukraine
A civilian holds a sign in front of Ukrainian troops at a checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. Pro-Russian rebels shot down two Ukrainian helicopters on Friday, killing two crew, as troops tightened their siege of separatist-held Slaviansk and Moscow accused Kiev of launching a "criminal" assault that wrecked hopes of peace. The sign reads, "We are peaceful people." REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
Civilians stand near Ukrainian troops at a checkpoint near the town of Slaviansk in eastern Ukraine
Civilians stand near Ukrainian troops at a checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. Pro-Russian rebels shot down two Ukrainian helicopters on Friday, killing two crew, as troops tightened their siege of separatist-held Slaviansk and Moscow accused Kiev of launching a "criminal" assault that wrecked hopes of peace. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
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A civilian talks with Ukrainian troops at a checkpoint near the town of Slaviansk in eastern Ukraine
A civilian talks with Ukrainian troops at a checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. Pro-Russian rebels shot down two Ukrainian helicopters on Friday, killing two crew, as troops tightened their siege of separatist-held Slaviansk and Moscow accused Kiev of launching a "criminal" assault that wrecked hopes of peace. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST TPX IMAGES OF THE DAY)
Civilians talk with Ukrainian troops at a checkpoint near the town of Slaviansk in eastern Ukraine
Civilians talk with Ukrainian troops at a checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. Pro-Russian rebels shot down two Ukrainian helicopters on Friday, killing two crew, as troops tightened their siege of separatist-held Slaviansk and Moscow accused Kiev of launching a "criminal" assault that wrecked hopes of peace. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
A Ukrainian military helicopter flies over a Ukrainian checkpoint near the town of Slaviansk in eastern Ukraine
A Ukrainian military helicopter flies over a Ukrainian checkpoint near the town of Slaviansk in eastern Ukraine May 2, 2014. Pro-Russian rebels shot down two Ukrainian helicopters on Friday, killing two crew, as troops tightened their siege of separatist-held Slaviansk and Moscow accused Kiev of launching a "criminal" assault that wrecked hopes of peace. REUTERS/Baz Ratner (UKRAINE - Tags: POLITICS CIVIL UNREST)
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