Operation Allied Force
The one particular F-117 that was gunned down was part of the American fleet involved in Operation Allied Force. The fleet was forced as part of the 1990 NATO-backed bombing of what was still known as Yugoslavia. It was the only Nighthawk to be lost in battle.
The Conflict
The conflict began in the autonomous region called Kosovo, where the majority of the population was Albanian-speaking Muslims. The reason for this conflict was that ethnic Serbians felt marginalized. If you look at history, many conflicts like this start for the same reasons.