This volume of collected papers takes stock of what has become known about the war in eastern Ukraine’s Donets Basin (Donbas) between April 2014 and mid-2020. It provides an introduction to the conflict and illustrates the key point of contention in the academic debate surrounding it—the question whether this war is primarily an internal Ukrainian phenomenon or the result of a covert Russian invasion. The contributions by recognized specialists from Ukraine, Russia, Germany, and Japan offe...