A helmet lays on the ground surrounded by shell casings, May 25, 2017, at Yokota Air Base, Japan. The 374 SFS 2017 Security Forces Advanced Combat Skills Assessment team regularly practiced firing various weapons including the M4 carbine assault rifle, M9 pistol, M249 light machine gun and the M203 grenade launcher in preparation for the Advanced Combat Skills Assessment competition at Andersen Air Force Base, Guam. (U.S. Air Force photo by Airman 1st Class Donald Hudson)