Challenging procedures
Soldiers from the Japan Ground Self-Defense Force, 34th Infantry Regiment, 1st Company, practice techniques used to challenge vehicles at Yokota Air Base, Japan, Feb. 9, 2015. A vehicle challenge is when a security force member commands a driver to turn off their engine, drop their keys out of the window, exit the vehicle and slowly get on the ground. (U.S. Air Force photo by Staff Sgt. Cody H. Ramirez/Released)