after being surrounded , and again in February 2015 in Debaltseve , on a key highway between Donetsk and Luhansk . The battles dealt devastating blows to the Ukrainian military , in terms of human lives and morale , and bolstered the confidence of the Russia - backed separatists . Russia and the separatists , meanwhile , may have their own motives for escalating the fighting now -- and their own reasons not to take it too far .