Operation Sky Monitor Operation Sky Monitor was a NATO mission to monitor unauthorized flights in the airspace of Bosnia - Herzegovina during the Bosnian War . The operation began in response to United Nations Security Council Resolution 781 , which established a ban on the use of military aircraft in Bosnian airspace , and requested the aid of member states in monitoring compliance . Beginning on October 16 , 1992 , NATO monitored violations of the no - fly zone using E - 3 Sentry NAEW aircraft based in Germany , Italy , Greece , and the United Kingdom . The operation documented more than 500 violations of the no - fly zone by April 1993 . In response to this high volume of unauthorized flights , the Security Council passed Resolution 816 , which authorized NATO to enforce the no - fly zone , and engage violators . In response , NATO deactivated Sky Monitor on April 12 , 1993 , transferring its forces to the newly established Operation Deny Flight . Background . On September 25 , 1991 , at the beginning of the Yugoslav wars , the United Nations Security Council issued Resolution 713 , which established " a general and complete embargo on all deliveries of weapons and military equipment to Yugoslavia " , with the goal of reducing violence and bloodshed throughout the country . In May , the Security Council reaffirmed the embargo in Resolution 757 , and added a provision for a naval force to monitor compliance with the embargo . In resolution 757 , the Council also called on states to " deny permission to any aircraft to take off , land in or overfly their territory if it is destined to land in or had taken off from the territory of the Federal Republic of Yugoslavia " , setting the precedent for later anti - air measures . In response to resolution 757 , NATO began to perform its first operations on behalf of the United Nations on July 16 , 1992 with Operation Maritime Monitor , which monitored violations of Security Council Resolutions by ships . As a part of Maritime Monitor , NATO dispatched E - 3 Sentry airborne early warning aircraft to the region to monitor sea traffic . These aircraft flew more than 200 missions over the course of the operation . On October 9 , 1992 , the Security Council passed resolution 781 . In the resolution , the Security Council expressed concern about the use of aircraft by the belligerents in the War in Bosnia and established a formal " ban on military flights in the airspace of Bosnia and Herzegovina " . It also called upon member states to help the United Nations Protection Force ( UNPROFOR ) in monitoring " compliance with the ban on military flights " . Shortly thereafter , on October 15 , NATO aircraft operating under Maritime Monitor began monitoring flights over Bosnia for the UN . The essential goal of this mission was to conduct surveillance in order to determine whether or not the various parties in the conflict were respecting the UN no - fly zone . The next day , October 16 , Operation Sky Monitor officially began when NATO planes expanded their monitoring with flight paths over the Adriatic . Operation . During Operation Sky Monitor , aircraft operated in two " orbits " , one over the Adriatic established on October 16 , and a second one over Hungary , established with the permission of the Hungarian government on October 31 . Both of these orbits operated 24 hours a day , providing constant surveillance of Bosnian airspace . The first flight over Hungary on October 31 was an important milestone in NATO history as it was the " first operational mission in a former Warsaw Pact nation " for the alliance . Even more significantly , Hungary agreed that if a NATO aircraft were attacked in its airspace , the Hungarian Air Force would provide support with Mikoyan - Gurevich MiG - 21 fighters . This support never became necessary , but it marked another important milestone , actual military cooperation between NATO and the former Warsaw Pact . The monitoring aircraft of Sky Monitor were initially drawn from the NATO Airborne Early Warning squadron based at NATO Air Base Geilenkirchen in Germany , but Aviano Air Base in Italy , Preveza in Greece , and Trapani in Italy were all used as forward operating bases . As the operation expanded , the British No . 8 Squadron RAF and the French E - 3F squadron at Avord Air Base were also used . All of these NATO forces fell under the authority of Allied Forces Southern Europe , commanded by Admiral Jeremy Boorda of the United States Navy . Eleven NATO countries provided personnel or aircraft for the operation : Belgium , Canada , Denmark , Germany , Greece , Italy , the Netherlands , Norway , Portugal , Turkey , and the United States . The rules of engagement for Sky Monitor were very restrictive . Because the purpose of the operation was to monitor , rather than prevent , unauthorized flights , participating aircraft were only authorized to use force in self - defense . Furthermore , under the rules of engagement , NATO forces were directed to take evasive action if attacked rather than engage an opponent if at all possible . As a result of the strict rules of engagement , no NATO forces were engaged in combat during Operation Sky Monitor . Sky Monitor documented many violations of the no - fly zone , the most significant of which came in March 1993 , when Serb aircraft bombed two Muslim villages . This violation , the first " combat violation " of the no - fly zone , led to calls for NATO to actively enforce the zone , rather than just monitoring compliance . Results . At the beginning of April 1993 , NATO had documented more than 500 violations of the no - fly zone over Bosnia , including violations from all sides in the conflict . Out of these numerous violations , however , NATO documented only one that it considered a " combat mission " . Although most of the violations were not combat missions , NATO had decided even before the end of Sky Monitor that the UN ban was ineffective . On December 18 , 1992 , the NATO members voted to enforce the no - fly zone with military force if requested by the United Nations . This escalation of NATO involvement also gained the crucial backing of US President - elect Bill Clinton in December , when he told the press that he had " been in favor of enforcing the no - fly zone for some time . " The UN called for NATO to use force in response to the " blatant violations of the ban on military flights in the airspace of Bosnia and Herzegovina " with Security Council Resolution 816 on March 31 , 1993 . The resolution authorized UN member states to " take all necessary measures " in order " to ensure compliance " with the no - fly zone . As a result of this new resolution , NATO deactivated Sky Monitor , and began Operation Deny Flight on April 12 , 1993 . Under Deny Flight , NATO forces continued to monitor and document unauthorized flights , but they were also authorized to enforce the zone and engage violators if necessary . Operation Sky Monitor was the first of many NATO air operations in the Balkans , including the more significant Operation Deliberate Force and Operation Allied Force . Sky Monitor was also NATO ' s first out of area air operation , and one of its first collaborative missions with the United Nations . Thus , it set the precedent for future NATO - UN cooperation , based on a model where NATO forces would use their superior technical expertise to assist the UN in pursuing its broader mission . Sky Monitor also had an impact on military policy , as it proved the utility of the E - 3 Sentry , NATO ' s principal aircraft in the operation , for monitoring missions under a wide variety of circumstances . Thus , the E - 3 became an important part of NATO ' s planning for later operations .