Rear Adm. John Spencer, Defense Threat Reduction Agency Nuclear Enterprise director, speaks during a dedication ceremony at the Defense Nuclear Weapons School at Kirtland Air Force Base, N.M., Jan. 10. During his speech, Spencer spoke about the 72 years of history throughout the schoolhouse and what it means to have the new replica of the iconic Mk6 Atomic Bomb training device in front of it. (U.S. Air Force photo by Staff Sgt. Kimberly Nagle)