Air Force Chief of Staff Gen. Norton Schwartz observes First Lieutenant Kenneth Bowman and Second Lieutenant Neil Bockus of the 12th Space Warning Squadron at Thule Air Base, Greenland, on Nov. 25, 2010, during a Thanksgiving visit. The 12th SWS is charged with operating, maintaining and securing the Ballistic Missile Early Warning System, which provides for missile warning and space surveillance. Thule Air Base, one of the six installations supported by the 21st Space Wing, is the U.S. Armed Forces' northernmost installation, located 750 miles north of the Arctic Circle. (U.S. Air Force photo/Staff Sgt. Sarah Beasley)