Portuguese Angola and Mozambique were seen as potential solutions to South Africa’s economic and security problems, and South Africa had worked with the Portuguese colonial government in the past. With both territories possessing large settler populations, friendly post-colonial régimes could be set up with South African military intervention, turning the former Portuguese colonies into buffer states and important allies in a hostile neighborhood. Furthermore, Angola’s developed infrastructure and rich resource wealth could help South Africa economically, as it felt increasingly isolated by the international community. 
Having the largest and most powerful military of the region, South Africa had the means to accomplish its objectives. Military bases in South-West Africa (Namibia) served as a useful staging ground for intervention in Angola. In addition to its own motivations, South Africa was encouraged to intervene by the United States, who felt that they were needed to counter the Cuban and Soviet support of the MPLA. After invitations from both UNITA and the FNLA in the early days of the civil war, South Africa made its first incursion into Angola in June of 1975. This action would be the first of twelve invasions by the SADF, which would be vital for the survival of UNITA as a viable military force. The continued involvement of South Africa forced the MPLA to rely on Cuban and Soviet military support throughout the civil war. The transition to a post-apartheid government in the early-90s and the independence of Namibia meant that South Africa would no longer intervene militarily in Angola. UNITA would have to depend on its other regional ally, Zaire, for continued support against the MPLA. 
Sharing a large border and deep cultural ties that went back to the Kongo kingdom, Zaire and Angola were strongly connected. Throughout the liberation war, Zaire served as a base of operations for the Bakongo-dominated FNLA and provided it significant military assistance. Besides the solidarity showed to their Bakongo kin, Mobutu’s Zaire had other important reasons for fighting the MPLA. Some of these were ideological; Mobutu was a staunch Cold War ally of the US and was highly critical of communism. His experience with Soviet-supported Katangese rebels in the late 1960s helped establish these views and when this group began to fight on the side of the MPLA in 1975, it only increased the animosity between Mobutu and the MPLA. Other aspects of the MPLA and Mobutu’s ideologies also clashed. While the MPLA espoused multi-racial and cosmopolitan views, Mobutu was a black nationalist with strong ideals of African authenticity. Starting in 1975, Zaire sent several battalions of regular soldiers as well as commando units into Angola, after unsupported FNLA guerillas proved ineffective. Even with significant weapons provided by the US and other Western nations, the Zairians were decisively defeated by the MPLA and their Cuban allies. In the disorganized retreat back into Zaire, the troops wrecked havoc on the countryside and abandoned large amounts of American weapons, exposing the US’s somewhat clandestine support of the FNLA. 