Don, a military working dog with the Provost Marshal Office, and his handler, Chad Twigger, search vehicles for hidden drugs or explosives at the New River Air Station, N.C., entrance gate, May 13, 2015. The dog’s presence at the gate serves as a deterrent to potential criminals and their detection abilities far exceed those of humans or machines. (U.S. Marine Corps photo by Cpl. Michelle Reif/Released.)