Without Cuban and Soviet backing, the MPLA would have never been able to defeat its opponents, who also had the support of foreign superpowers. The initial reasons for United States intervention in Angola were primarily economic.  American oil companies were well established there since the discovery of oil in the 1950s, and in order to protect these interests, the US supported the Portuguese during the liberation war.  By the time the Portugal was preparing to leave the continent in 1974, the threat of communist takeover by the MPLA with Cuban and Soviet support influenced the US to fund alternative groups to prevent a communist victory. 