Operation Deny Flight was a North Atlantic Treaty Organization (NATO) operation that began on 12 April 1993 as the enforcement of a United Nations (UN) no-fly zone over Bosnia and Herzegovina. The United Nations and NATO later expanded the mission of the operation to include providing close air support for UN troops in Bosnia and carrying out coercive air strikes against targets in Bosnia. Twelve NATO members contributed forces to the operation and, by its end on 20 December 1995, NATO pilots had flown 100,420 sorties.
The operation played an important role in shaping both the Bosnian War and NATO. The operation included the first combat engagement in NATO's history, a 28 February 1994 air battle over Banja Luka, and in April 1994, NATO aircraft first bombed ground targets in an operation near Goražde. These engagements helped show that NATO had adapted to the post–Cold War era and could operate in environments other than a major force-on-force engagement on the plains of Central Europe. Cooperation between the UN and NATO during the operation also helped pave the way for future joint operations. Although it helped establish UN–NATO relations, Deny Flight led to conflict between the two organizations. Most notably, significant tension arose between the two after UN peacekeepers were taken as hostages in response to NATO bombing.
The operations of Deny Flight spanned more than two years of the Bosnian War and played an important role in the course of that conflict. The no-fly zone operations of Deny Flight proved successful in preventing significant use of air power by any side in the conflict. Additionally, the air strikes flown during Deny Flight led to Operation Deliberate Force, a massive NATO bombing campaign in Bosnia that played a key role in ending the war.
Background and Operation Sky Monitor
In October 1992, at the beginning of the Bosnian War, the United Nations Security Council passed Resolution 781. This resolution prohibited unauthorized military flights in Bosnian airspace. Following the resolution, NATO began Operation Sky Monitor during which NATO forces monitored violations of the no-fly zone, without taking any military action against violators. By April 1993, NATO forces had documented more than 500 violations of the no-fly zone. In response to these "blatant" violations of Bosnian air space, and implicitly of resolution 781, the UN Security Council issued Resolution 816.
While Resolution 781 prohibited only military flights, Resolution 816 prohibited all flights in Bosnian air space, except for those expressly authorized by the UN Flight Coordination Center in Zagreb. The resolution also authorized UN member states to "take all necessary measures ... to ensure compliance" with the no-fly zone restrictions. In response to this resolution, NATO commenced Operation Deny Flight on 12 April 1993. Initially Deny Flight was intended only to enforce the no-fly zone; however several NATO members, including the United States, were eager to find ways to end the war and improve the situation of civilians, and hoped that military action could do so. The US had already taken unilateral actions to aid civilians caught in the conflict by dropping humanitarian supplies into Bosnia under Operation Provide Promise, and many US officials argued for the use of military force. These officials were eager to expand US air operations through Deny Flight, hoping that an aggressive no-fly zone and possible air strikes would end the conflict more quickly. NATO forces suffered its first loss on the second day of operations, when a French Mirage 2000 crashed in the Adriatic Sea due to mechanical failure. The pilot ejected safely.
Enforcement of no-fly zone
After its adoption, Operation Deny Flight was relatively successful in preventing fixed-wing aircraft from flying over restricted air space in Bosnia. During the monitoring phase of Operation Sky Monitor, unauthorized fixed-wing flights averaged twenty per month, but during Deny Flight, the average was three. During the conflict, there were only an estimated 32 fixed-wing military aircraft in Bosnia, all of them former Yugoslav National Army planes under the control of the Bosnian Serbs. Thus, NATO primarily needed to prevent incursions into Bosnian airspace from Croatia and Serbia.