Origin of the conflict

Yugoslavia emerged after World War I, from the territories of the former Ottoman Empire. The nation united a number of Slavic ethnic groups, each with their individual desires for statehood. For most of its existence successive totalitarian governments forcibly united the groups under a single nation.

Chronological timeframe

1919 – Yugoslavia created under the Treaty of Versailles.
1980 – Communist leader, Josep Broz Tito died.
1987 – Slobodan Milosevic dominated the federal government. A number of the republics moved towards independence, first Slovenia and after Croatia. Milosevic responded with force, both in Slovenia and then in Serb-dominated parts of Croatia.
1991 – UN imposed an arms embargo on Yugoslavia in response to the impending Bosnian crisis.
1992 – The Bosnian republic intended to hold an independence referendum, supported by the Bosnian Muslim majority and opposed by a Bosnian Serb minority (supported by Milosevic).
1993 – International Criminal Tribunal for the Former Yugoslavia (ICTY) created by the UN Security Council.
1994 – ¼ of a million people dead and more than 2 ½ million displaced in the region.
1995 – NATO bombed Serb positions around Belgrade, the Bosnian war ended with the Dayton Peace Accords which required both the UN and NATO involvement.
1999 – Major NATO bombing campaign.
1999 – Milosevic accepted peace conditions and NATO forces moved into Kosovo.
2002 – UN mission in the region ended and responsibility was handed over to a European Union police mission.

Actors involved:

Serbia
The dominant political force in Yugoslavia during the 1980s and beyond. Led by Slobodan Milosevic with a post-cold-war history of ethnic cleansing. The Serb government funded Bosnian Serb militias, led by General Ratko Mladic, killing, raping and terrorising Bosnian Muslims.

Croatia
Large ethnic group within the original Yugoslavia. Previously the Croatian Ustache militia had helped the German army, during World War II, to round up ethnic Serbs.

Bosnia and Herzegovina
Declared independence in 1992, with a significant ethnic division between the Bosnian Muslim majority and Bosnian Serb minority. Serb militias, funded by Milosevic, violently drove Muslims out of certain areas to create pockets of Serb majority within Bosnia and Herzegovina.

Reaction of the international community
Originally the crisis in Yugoslavia was largely in the realm of the UN, however, NATO became increasingly involved in the region during the 1990s. Many of the initial efforts of these international organisations were ineffective and Bosnian calls for stronger international effort were rebuffed.

Sources
Allphin Moore, Jr. J and Pubantz, J. (2006) The New United Nations
International Organization in the Twenty-First Century, Pearson: Harlow.