epa04630610 Pro-Russian rebels stand at an twin-barrelled anti-aircraft gun installed in Debaltseve, Donetsk area, Ukraine, 21 February 2015. Ukrainian government forces pulled out of the strategic eastern city of Debaltseve on 18 February 2015. Pro-Russian rebels and Ukrainian government forces are making preparations for an exchange of prisoners in conflict-hit eastern Ukraine and lists of prisoners had already been exchanged between the rebels and the Ukrainian government, a rebel spokeswoman said 21 February. EPA/ALEXANDER ERMOCHENKO