U.S. Air Force F-22 Raptor aircraft with the 192nd Fighter Wing participate in Red Flag at Nellis Air Force Base, Nev., March 5, 2013. Red Flag is an advanced aerial combat training exercise held four to six times a year to train pilots from the U.S., NATO and other allied countries for real combat situations. (DoD photo by Senior Airman Matthew Lancaster, U.S. Air Force/Released)