NATO intervention in Bosnia and Herzegovina - Wikipedia

Today in American Military History -- 1993
Bosnia: USS 'Theodore Roosevelt' (CVN-71) & NATO a/c initiate no-fly zone

NATO involvement in the Bosnian War and the Yugoslav Wars in general began in February 1992, when the alliance issued a statement urging all the belligerents in the conflict to allow the deployment of United Nations peacekeepers. While primarily symbolic, this statement paved the way for later NATO actions. On November 16, 1992, the Security Council issued Resolution 787, which called upon member states to "halt all inward and outbound maritime shipping in order to inspect and verify their cargos" to ensure compliance with sanctions.

In response to this resolution, NATO deactivated Maritime Monitor on November 22, and replaced it with Operation Maritime Guard, under which NATO forces were authorized to stop ships and inspect their cargos. Unlike Sky Monitor and Maritime Monitor, this was a true enforcement mission, not just a monitoring one. NATO's air mission also switched from monitoring to enforcement. The Security Council issued Resolution 816, which authorized states to use measures "to ensure compliance" with the no-fly zone over Bosnia. In response, on April 12, 1993, NATO initiated Operation Deny Flight which was tasked with enforcing the no-fly zone, using fighter aircraft based in the region.