While we are predominantly interested in capitalist imperialism, we cannot avoid discussing the activities of the so-called "socialist" nations (such as the Soviet Union, China, etc.). Given that imperialism has an economic base caused in developed capitalism by, in part, the rise of big business organised on a wider and wider scale, we should not be surprised that the state capitalist ("socialist") nations are/were also imperialistic. As the state-capitalist system expresses the logical end point of capital concentration (the one big firm) the same presses that apply to big business will also apply to the state capitalist nation (see last section).
Given this, it comes as no surprise that the state-capitalist countries also participated in imperialist activities, adventures and wars, although on a lesser scale and for slightly different reasons. As can be seen by Russia's ruthless policy towards her satellites, Soviet imperialism was more inclined to the defence of what she already had and the creation of a buffer zone between herself and the West. This is not to deny that the ruling elite of the Soviet Union did not try to exploit the countries under its influence. For example, in the years after the end of the Second World War, the Eastern Block countries paid the U.S.S.R. millions of dollars in reparations. As in private capitalism, the "satellite states were regarded as a source of raw materials and of cheap manufactured goods. Russia secured the satellites exports at below world prices. And it exported to them at above world prices." [Andy Anderson, Hungary '56, pp. 25-6]
The Soviet elite also aided "anti-imperialist" movements when it served their interests and placed them within the Soviet sphere of influence (along with US pressure which closed off other options). Once the Stalinist parties had replaced the local ruling class, trade relations were formalised between the so-called "socialist" nations for the benefit of both the local and Russian rulers. In a similar way, and for identical needs, the Western Imperialist powers supported murderous local capitalist and feudal elites in their struggle against their own working classes, arguing that it was supporting "freedom" and "democracy" against Soviet aggression.
Needless to say, the form and content of the state capitalist domination of its satellite countries was dependent on its own economic and political structure and needs, just as traditional capitalist imperialism reflected its needs and structures. Part of the difference was, of course, the need to plunder these countries of commodities to make up for shortages caused by central planning (in contrast, capitalist imperialism tended to export goods).
Just as capitalist domination saw the transformation of the satellite's countries social relations from pre-capitalist forms tin favour of capitalist ones, the domination of "socialist" nations meant the elimination of traditional bourgeois social relations in favour of state capitalist ones. As such, the nature and form of imperialism was fundamentally identical and served the interests of the appropriate ruling class in each case.
Therefore, imperialism is not limited to states based on private capitalism — the state capitalist regimes have also been guilty of it. This is to be expected, as both are based on minority rule, the exploitation and oppression of labour and the need to expand the resources available to it.