Master Sgt. Sibyl Reyes, the first sergeant for the 28th Contracting Squadron, questions noncommissioned officers during Backbone University, a course focused on joint leadership development, Sept. 5, 2017, on Ellsworth Air Force Base, S.D. First sergeants facilitated conversations about cooperating with our sister services and other key Air Force issues. (U.S. Air Force photo by Airman 1st Class Thomas Karol)