El Salvador
It was between the military-led government of El Salvador and the Farabundo Martà National Liberation Front (FMLN), a coalition or umbrella organization of five left-wing militias. Significant tensions and violence had already existed, before the civil war's full outbreak, over the course of the 1970s.
The United States supported the Salvadorian military government. The conflict ended in the early 1990s. Some 75,000 people were killed.
Read more about this topic: Central American Crisis