The war, as a social phenomenon, in its diverse forms of appearance, dates back to the first organizational forms of human community. Therefore different opinions may be found in the literature as regards the number of wars waged in the history. But, a more important issue for this paper is a theoretical determination of war, understanding of its contents, the forces taking part in it, as well as the ways of resolving it. This paper presents an analysis of opinions on war set forth in the Defense Strategy of the State Union of Serbia and Montenegro, as the highest doctrinal document determining the sector of security and defense of the member states and the State Union of Serbia and Montenegro.