Within Marxist theory, modern warfare is described as existing as result of capitalism. Marxist theory states that all modern wars are caused by competition for resources and markets between great and imperialist powers, claiming these wars are a natural result of the free market and a class system.
Marxist philosopher Rosa Luxemburg theorized that imperialism was the result of capitalist countries needing new markets. Expansion of the means of production is only possible if there is a corresponding growth in consumer demand. Since the workers in a capitalist economy would be unable to fill the demand, producers must expand into non-capitalist markets to find consumers for their goods, hence driving imperialism.
Vladimir Lenin expanded upon Marx's ideas, providing an analysis of what Lenin described as monopoly capitalism. In his theory, Lenin suggested that as capitalism developed as a system, monopoly capitalism was the highest stage of its development. According to Lenin, "imperialism is capitalism" when "the formation of international capitalist monopolies will share the world among themselves and the territorial division of the whole world among the greatest capitalist powers is completed".
In this way, Lenin is suggesting that capitalist powers will cause wars with weaker nations to increase their holding of monopoly capital. As capitalism develops, its natural progression is for core capitalist nations to exploit those on the periphery through imperialist wars in search of new markets and resources. Lenin's theory provided the origins of the world-systems theory.