Deputy Defense Secretary Bob Work tours a missile silo maintenance training facility as he visits the base to meet with nuclear enterprise airmen on Minot Air Force Base, N.D., Feb. 11, 2015. Deputy Defense Secretary Bob Work tours a missile silo maintenance training facility as he visits the base to meet with nuclear enterprise airmen on Minot Air Force Base, N.D., Feb. 11, 2015. SHARE: Download: Full Size (0.95 MB) Tags: photo essays Credit: VIRIN: 865088-Q-YJL05-244.jpg Photo Gallery