OSAN AIR BASE, Republic of Korea -- This groundbreaking initiative is the first ever U.S. Air Force contracted aerial refueling to support their fighter aircraft. The mission supported F-16 Fighting Falcons assigned to the 51st Fighter Wing, enroute to Commando Sling 23. CS23 is a Pacific Air Forces-sponsored bilateral training event with the Republic of Singapore Air Force designed to increase interoperability and improve alliance capability.