Nigeria is an amalgam of rival ethnic groups pitched against each other in a contest for power and resources that have reflected in the political processes, sometimes threatening the corporate existence of the country. Right from the constitutional conferences organized during the colonial era down to the ones organized after independence, the question of an acceptable system of co-existence has been contentious. However, the intervention of the military in the political affairs of the country and their long duration in governance succeeded in abating the full manifestation of ethno-nationalism. But the return of the country to democracy in 1999 has enabled the suppressed ethno-nationalism grievances to explode, throwing up issues beyond the capacities of democratic institutions. Ethno-nationalism has become a threat to the survival of the nation's nascent democracy and its existence. As a result, the democratic government has resorted to the tactics of military administration in the management of these challenges. This paper examines the state's response to an emboldened ethno-nationalism and its implications on the process of democratization. It adopted both descriptive and analytical methods, using the theory of instrumentalism to explain the factors responsible for ethno-nationalism.