Several incidents in the mid- to late 1970s contributed to the MPLA regime's reliance on Soviet military aid and the presence of Cuban troops. The first incident occurred on March 8, 1977, when the National Front for the Liberation of the Congo (Front National pour la Libération du Congo--FNLC), a political opposition group hostile to Zaire's President Mobutu, launched an attack from Angola on Zaire's economically vital Shaba Province. Although the Zaire government halted the invasion with the aid of Moroccan troops, Mobutu accused the MPLA of having instigated the attack. In return, Neto charged Mobutu with harboring and militarily supporting both the FNLA and FLEC. The MPLA government, faced with continuing border violations and engaged in recriminations with the Mobutu regime, requested and received an increase in the number of Cuban troops.

Another incident brought factionalism in the MPLA leadership into sharp focus. Two ultraleftists, minister of interior and Central Committee member Nito Alves and Central Committee member José Van Dúnem, had become critical of the government's economic policies, which both men considered too moderate. They also criticized the government leadership for its heavy representation of whites and mestiços. In October 1976, the MPLA condemned Alves for factionalism and abolished his ministry. The government set up a commission of inquiry that investigated reports that Van Dúnem and Alves had purposely caused food shortages to stir up discontent. The commission found the men guilty and expelled them from the Central Committee in May 1977. Later that month, Alves and Van Dúnem led an uprising in the capital and called for mass demonstrations outside the presidential palace. The uprising failed, but Alves, Van Dúnem, and their followers seized a number of senior government leaders, whom they later killed.

The Neto regime, already alarmed by party factionalism and the number of members who did not actively support the party's MarxistLeninist objectives, conducted a massive purge. It reorganized the party and the mass organizations, many of which had supported Alves and Van Dúnem. The commissars and directing committees in eight provinces, appointed by Alves when he had been minister of interior, were removed. Thousands of Alves supporters, referred to as Nitistas, were dismissed from their positions and detained. All mass organizations were made subordinate to the MPLA. Finally, to achieve these changes, national and provincial restructuring committees were set up. By December 1980, the party had shrunk from 110,000 members to about 32,000 members.

Data as of February 1989