Nigeria has experienced substantial internal insecurity. Mass violence erupted frequently. During the five years immediately preceding the civil war, 124 riots were reported. The civil war between 1967 and 1970 produced about 2 million deaths. Regime instability also came to characterize political life, which was punctuated by a members of coups between 1966 and 1985 several attempted coups, often accompanied or followed by violent retribution and periodic government reorganizations and leadership changes. Primary sources to potential dissent and opposition were illegal aliens, sectional-ethnic cleavages, religious sectarianism, the labor force and labor unions, and intellectuals. Although none of these groups was capable of overthrowing the government or of offering an alternative political formula, recurring and sometimes widespread violence involving one or more of these interests precipitated major security crises.

Nigeria's relative wealth, particularly during the oil-fueled boom of the 1970s, was a magnet for alien migrant laborers, many of whom entered illegally. Relations with these workers were tense and marked by two large-scale expulsions. In early 1983, Nigeria ordered all foreigners illegally residing and working in the country to leave within a matter of weeks most had entered under the ECOWAS protocol on free movement of people and goods but had overstayed. At least 1.3 million West Africans--mainly from Ghana, Niger, Chad, and Cameroon--were expelled despite international protests. A second campaign to expel 700,000 illegal aliens took place in May 1985, but it was not clear how many were actually repatriated.

Nigeria's ethnic and religious heterogeneity was the most persistent source of violent conflicts. Although the issue of secession based on regional ethnic nationalism was settled by the unsuccessful Biafran experience and later muted politically by the abolition of the regions in favor of twenty-one states, the assertion or reassertion of the country's primordial "nations" remained a latent threat to national unity.

Data as of June 1991