A wolf looks into the camera at the 30 km (19 miles) exclusion zone around the Chernobyl nuclear reactor in the abandoned village of Orevichi, Belarus, March 2, 2016. What happens to the environment when humans disappear? Thirty years after the Chernobyl nuclear disaster, booming populations of wolf, elk and other wildlife in the vast contaminated zone in Belarus and Ukraine provide a clue. (Photo by Vasily Fedosenko/Reuters)

October 25, 2009; London,UK; The mascot for the Tampa Bay Buccaneers watches a cheerleader during the NFL International Series game against the New England Patriots at Wembley Stadium. (Photo by David Wilkinson/Offside Sports)

Trevor Olson, from Minnesota, dressed as the character “Joker”, poses for a photograph at New York's Comic Con convention, October 9, 2014, in New York City. The event draws thousands of costumed fans, panels of pop culture luminaries and features a sprawling floor of vendors in a space equivalent to more than three football fields in Javits Center. (Photo by Shannon Stapleton/Reuters)

Sports Finalist – Ian MacNicol. Michalina Kwasniewska of Poland competes in the Women's high jump during day one of The European Athletics U23 Championships 2013 on July 11, 2013 in Tampere, Finland. (Photo by Ian MacNicol/Agence France-Presse)

British model Jean Shrimpton at London Airport (now Heathrow), 5th June 1967. (Photo by Dove/Express/Getty Images)

Storm clouds gather over the scene outside the Jewish Community Center in Leawood, Kansas following a shooting, on April 13, 2014. (Photo by John Sleezer/Kansas City Star/MCT)

A rainbow is seen near a cloud south of Corvallis, Ore., Monday, May 19, 2014. (Photo by Andy Cripe/AP Photo/The Corvallis Gazette-Times)

Throughout the course of the long war in Afghanistan, Coalition troops have relied on thousands of military working dogs to help keep them safe, and make their jobs easier. The dogs are trained to detect explosives, to find illegal drugs, to search for missing comrades, or target enemy combatants. Not only are they active on the front lines, but behind the lines they serve as therapy dogs, service dogs, and loyal companions. They also share the same risks as the ground troops, suffering injuries and sometimes death on the battlefields. Gathered here are images of these dogs and their handlers in Afghanistan and back home, from over the past several years, part of the ongoing series here on Afghanistan.