Later , Kosovar Albanians started an insurgency against Belgrade when the Kosovo Liberation Army was founded in 1996 . Armed clashes between the two sides broke out in early 1998 . A NATO-facilitated ceasefire was signed on 15 October , but both sides broke it two months later and fighting resumed . When the killing of 45 Kosovar Albanians in the Račak massacre was reported in January 1999 , NATO decided that the conflict could only be settled by introducing a military peacekeeping force to forcibly restrain the two sides . After the Rambouillet Accords broke down on 23 March with Yugoslav rejection of an external peacekeeping force , NATO prepared to install the peacekeepers by force . The NATO bombing of Yugoslavia followed , an intervention against Serbian forces with a mainly bombing campaign , under the command of General Wesley Clark . Hostilities ended 2 ½ months later with the Kumanovo Agreement . Kosovo was placed under the governmental control of the United Nations Interim Administration Mission in Kosovo and the military protection of Kosovo Force ( KFOR ) . The 15-month war had left thousands of civilians killed on both sides and over a million displaced
Račak massacre
Račak massacre
Yugoslav Wars