In mid-1996, the Air Force, in response to budget cuts, and changing world situations, began experimenting with Air Expeditionary organizations. The Air Expeditionary Force (AEF) concept was developed that would mix Active-Duty, Reserve and Air National Guard elements into a combined force. Instead of entire permanent units deploying as "Provisional" as in the 1991 Gulf War, Expeditionary units are composed of "aviation packages" from several wings, including active-duty Air Force, the Air Force Reserve Command and the Air National Guard, would be married together to carry out the assigned deployment rotation.