Bosnian War: NATO launches Operation Deliberate Force against Bosnian Serb forces.

The Bosnian War was an international armed conflict that took place in Bosnia and Herzegovina between 1992 and 1995. Following several earlier violent incidents, the war is commonly seen as having started on 6 April 1992 when the newly independent Republic of Bosnia and Herzegovina was internationally recognized. It ended on 21 November 1995 when the Dayton Accords were initialed. The main belligerents were the forces of the government of the Republic of Bosnia and Herzegovina, and those of the breakaway proto-states of the Republic of Herzeg-Bosnia and the Republika Srpska which were led and supplied by Croatia and Serbia, respectively.

The North Atlantic Treaty Organization, also called the North Atlantic Alliance, is an intergovernmental military alliance between 32 member states—30 in Europe and 2 in North America. Founded in the aftermath of World War II, NATO was established with the signing of the North Atlantic Treaty in 1949. The organization serves as a system of collective security, whereby its independent member states agree to mutual defence in response to an attack by any external party. This is enshrined in Article 5 of the treaty, which states that an armed attack against one member shall be considered an attack against them all.

Operation Deliberate Force was a sustained air campaign conducted by NATO, in concert with the UNPROFOR ground operations, to undermine the military capability of the Army of Republika Srpska (VRS), which had threatened and attacked UN-designated "safe areas" in Bosnia and Herzegovina during the Bosnian War, with the Srebrenica genocide and Markale massacres precipitating the intervention. The shelling of the Sarajevo marketplace on 28 August 1995 by the VRS is considered to be the immediate instigating factor behind NATO's decision to launch the operation.