Armed pro-Russian activists stand guard next to a barricade at a checkpoint outside the eastern Ukrainian city of Slavyansk on April 24, 2014 after Ukrainian troops left. Up to five insurgents were killed when Ukraine's military on Thursday launched an assault on the flashpoint rebel-held town of Slavyansk, sending in armoured vehicles and a helicopter, AFP journalists in the town reported. AFP PHOTO/ GENYA SAVILOV        (Photo credit should read GENYA SAVILOV/AFP/Getty Images)