The self-styled mayor of Slaviansk, Vyacheslav Ponomaryov, leaves a news conference in the mayor’s office in Slaviansk on April 26, 2014. Separatists in the eastern Ukrainian city of Slaviansk are ready to exchange a group of international observers they are holding for fellow rebels who are in the custody of the Ukrainian authorities, Ponomaryov said on Saturday. (REUTERS/Gleb Garanich)