U.S. Air Force Lt. Gen. Sid Clarke, left, Commander of Continental United States North American Aerospace Defense Command Region and First Air Force (Air Forces Northern), passes the 601st Air and Space Operations Center (601st AOC) flag to Col. Thomas Cucchi during a change of command ceremony held here Nov. 20, 2012. The 601st AOC is responsible for detecting, deterring, defending and if necessary, defeating any aviation threat to the citizens of the United States and to U.S. critical infrastructure. (U.S. Air Force photo by Lisa Norman/Released)