Chief among the regional powers involved in Angola were Zaire and South Africa.  Both countries had strong motivations for their presence in Angola and importantly the means to affect the course of the war.  The rise of Black Nationalism and the decolonization of many countries in the region posed a major threat to the survival of the apartheid régime of South Africa.  Politically and economically based on a persistent system of racial oppression and exploitation, South Africa, as well as the other remaining settler colony, Rhodesia (now Zimbabwe), was under heavy international pressure to grant rights to its African majority and faced various boycotts and trade embargos as a result. 