Senior Airman Marcus Miller, 28th Security Forces Squadron patrolman, provides cover in a defense fighting position during small unit tactics training at Ellsworth Air Force Base, S.D., Sept. 12, 2014 during an Operational Readiness Exercise. Defense fighting position provides frontline perimeter security with interlocking fields to protect resources from all directions a vital element of small unit tactics. (U.S. Air Force photo by Senior Airman Zachary Hada/Released)