http://en.wikipedia.org/wiki/Decolonization

The Soviet Union sought to effect the abolishment of colonial governance by Western countries, either by direct subversion of Western-leaning or -controlled governments or indirectly by influence of political leadership and support. Many of the revolutions of this time period were inspired or influenced in this way. The conflicts in Vietnam, Nicaragua, Congo, and Sudan, among others, have been characterized as such.

Most Soviet leaders expressed the Marxist-Leninist view that imperialism was the height of capitalism, and generated a class-stratified society. It followed, then, that Soviet leadership would encourage independence movements in colonized territories, especially as the Cold War progressed. Though this was the view expressed by their leaders, such interventions can be interpreted as the expansion of Soviet interests (establishing the Iron Curtain), not just as aiding the oppressed peoples of the world. Because so many of these wars of independence expanded into general Cold War conflicts, the United States also supported several such independence movements in opposition to Soviet interests.

During the Vietnam War, Communist countries supported anti-colonialist movements in various countries still under colonial administration through propaganda, developmental and economic assistance, and in some cases military aid. Notably among these were the support of armed rebel movements by Cuba in Angola, and the Soviet Union (as well as the People's Republic of China) in Vietnam.