In 1999, the AV-8B participated in NATO's bombing of Yugoslavia during Operation Allied Force. Twelve Harriers were split evenly between the 24th and 26th Marine Expeditionary Units (MEU). AV-8Bs of the 24th MEU were introduced into combat on 14 April and over the next 14 days flew 34 combat air support missions over Kosovo. During their six-month deployment aboard USS "Nassau", 24th MEU Harriers averaged a high mission-capable rate of 91.8%. On 28 April, the 24th MEU was relieved by the 26th MEU, based on . The first combat sorties of the unit's AV-8Bs occurred two days later, one aircraft being lost. The 26th MEU remained in the theater of operations until 28 May, when it was relocated to Brindisi, Italy.