Combat operations begin in Operation Allied Force, the NATO air campaign against Yugoslavia. US aircraft fly about two-thirds of the 45,000 sorties, pressuring Serb leader Slobodan Milosevic to withdraw his forces from Kosovo.
The Pentagon has concluded a new agreement to buy laser-guidance kits that turn rockets into drone-killing weapons. BAE Systems and the Defense Department announced a framework deal of up to seven years for 25,000 Advanced Precision Kill Weapon System guidance kits annually for the U.S. military.