The varied reasons for the country’s breakup ranged from the cultural and religious divisions between the ethnic groups making up the nation, to the memories of WWII atrocities committed by all sides, to centrifugal nationalist forces. However, a series of major political events served as the catalyst for exacerbating inherent tensions in the Yugoslav republic. Following the death of Tito in 1980, provisions of the 1974 constitution provided for the effective devolution of all real power away from the federal government to the republics and autonomous provinces in Serbia by establishing a collective presidency of the eight provincial representatives and a federal government with little control over economic, cultural, and political policy.

https://history.state.gov/milestones/1989-1992/breakup-yugoslavia