This article precedes a large-scale study of the ethics of war in the USSR. The text deals with the problem of finding moral argumentation in the Russian Marxist tradition of understanding of war in 1910–1930s. Lenin, developing the ideas of Marx and Clausewitz, formulated that war is continuation of politics, which in turn is an expression of the class struggle. This thesis was sometimes taken as evidence of a rejection of the ethical consideration of war. However, a closer study of the literature and comparative research of the Bolsheviks theorists’ attitudes to militarism and pacifism, can lead to the conclusion that the ethical view on war was not completely alien to the Soviet authors. The typology of war, peculiar to the Russian Marxism of the specified period, is given, and the main strategies of moral legitimization of war are also designated. At the end of the article, the question of the complexity of studying the soviet ethics of war in the context of the homogenization of philosophical and military discourses in the USSR is considered. However, it is concluded that this institutional feature of Soviet science and philosophy manifested itself over time, that the reduction in the possibility of free thought and discussion gradually increased. Accordingly, in the writings of the 1920s and 1930s, we can try to discover the original Soviet ethics of war and fix various points of view and positions on the issues of the moral limitation of war. The article ends with the definition of the directions of further development of the subject. These tasks are: differentiation of the generalized views on the moral dimension of war presented in this article, clarification the dynamics and forms of the Soviet moral theory of war canon, and identification the differences between Lenin’s and Stalin’s approaches to understanding the war.