Marines keep an eye on the sky in Alaska
Marine Master Sgt. Brad Barber, the senior air director for Marine Air Control Squadron-1, monitors a three-dimensional air defense radar at their radar site set up on Joint Base Elmendorf-Richardson, Alaska, while directing Air Force aggressor pilots as they simulate aerial combat during Exercise Northern Edge 11, June 14, 2011. (U.S. Marine photo/Cpl. Marionne T. Mangrum)