Arguably the Soviets had an official state ideology that rationalized aggressive expansionism and imperialism far more readily than what guided diplomacy and military policy for the Western powers.
„Marx himself argued, back in the 1880s, that the movement toward a global communist future necessarily had to involve spreading out the borders of socialist Russia. Marx explained: »If the Russian Revolution becomes the signal for a proletarian revolution in the West, so that both complement each other, the present Russian common ownership of land may serve as the starting-point for a communist development.« Soviet expansionism, the »desire for world domination,« was consistent with this Marxist communist idea: the Soviet Union would be a »signal for a proletarian revolution in the West.«
There are those Sovietologists and scholars of the Cold War who would ignore Marxian ideology as they propose to understand the behavior of the USSR. For them it was a mere epiphenomenon, not a guiding doctrine. Yet that ideology held that capitalistic nations, in an effort to create foreign markets, must necessarily be imperialistic. And the military of such nations were supposed to be bent on securing those markets coercively, so socialist countries such as the USSR needed to prepare for this. Ergo, the USSR must achieve global dominance lest capitalist nations do so.
It is true that capitalists want to reach foreign markets but by all accounts they would want to do this peacefully, through trade instead of military conquest. This of course doesn’t mean that the Western governments were in no way responsible for a good deal of the malfeasance during the Cold War. But arguably the Soviets had an official state ideology that rationalized aggressive expansionism and imperialism far more readily than what guided diplomacy and military policy for the Western powers.”