ELLSWORTH AIR FORCE BASE, S.D. -- Airman 1st Class Kenneth Gadid, 28th Civil Engineer Squadron heating, ventilation and air conditioning technician, takes up a defensive position against a simulated ground attack during a Phase II Operational Readiness Exercise, Sept. 16. Airmen are tested in the exercise with simulated attacks and scenarios. (U.S. Air Force photo/Airman 1st Class Anthony Sanchelli)