Why do some wars recur and others do not? Depending on how one counts, the rate of war recurrence varies between 25 and 75 percent. While statistical studies suggest recurrence to be linked with the conditions created during the war and the opportunities present after conflict resolution, serious attempts to unpack war as a social process at the theoretical level are noticeably lacking. In this presentation, I offer a novel explanation of war recurrence. Based on the works of Niklas Luhmann, a modern systems theoretical framework is introduced that conceptualizes war as a (dys-)functional or parasitical system. This theoretical reconceptualization allows the study of the operations of the war system along the communicative distinction between ‘friend’ and ‘enemy’. Moreover, within the Luhmannian framework, the social and temporal dimensions of war are highlighted. To put it differently, the theoretical perspective of war as a system enables us to study the processes within and outside of war. Based on four empirical examples—the wars in Kosovo, Chechnya, Liberia, and Congo—I argue that wars which witness the isolation of a major war grouping and a simultaneous linear progression of hostilities towards a decisive outcome on the battlefield are more likely to end in the first place. Furthermore, if a war system manages to structurally couple with its environment—that is, to link the continuation of its own operations with that of other functional systems—then the war is more likely to recur.