Operation Eagle Eye was an operation before the 1999 Kosovo War to monitor Kosovo's compliance with the United Nations Security Council Resolution 1199 - which in part "Demands that all parties, groups and individuals immediately cease hostilities and maintain a ceasefire in Kosovo, Federal Republic of Yugoslavia" and that the Federal Republic of Yugoslavia "cease all action by the security forces affecting the civilian population and order the withdrawal of security units used for civilian repression."[1].
In an October 15th 1998 agreement with NATO, Yugoslavia agreed that unarmed surveillance aircraft, and International Observers on the ground could monitor its compliance. Operation Eagle was the name of the aerial component of this monitoring, which began October 17th, 1998. Operation Eagle Eye worked in concert with these 1400 ground observers in Kosovo. As a result of a Yugoslav troop movements and other forms of non-compliance the ground observers were withdrawn due to "an unacceptable level of risk to the peace support verification mission"[2], resulting in an end to aerial verification on March 24, 1999.
NATO - Operation Eagle Eye: [3]