French firemen wearing chemical protective suits take part in a mock chemical attack exercise at the Geoffroy Guichard stadium in Saint-Etienne, France, April 4, 2016 in preparation of security measures for the UEFA 2016 European Championship. (Photo by Robert Pratta/Reuters)

A girl plays with coloured chicks for sale prior to Easter celebrations in Byblos, Lebanon on March 22, 2015. (Photo by Jamal Saidi/Reuters)

Izzy Paskowitz helps Nixee Grace Chanowsky, 4, catch a wave Monday, August 18, 2014 at Wrightsville Beach, N.C. during the Annual Surfers Healing event for children with autism. Hundreds of people made their way to the beach to watch and cheer on the camp that was founded by Israel and Danielle Paskowitz. (Photo by Mike Spencer/AP Photo/The Star-News)

Model Natasha Poly poses on the red carpet as she arrives for the screening of the film “Carol” in competition at the 68th Cannes Film Festival in Cannes, southern France, May 17, 2015. (Photo by Eric Gaillard/Reuters)

Three workers demonstrating the different types of gas masks used in mine rescue work. (Photo by Fox Photos/Getty Images). December 1925

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.

“Strike Through The Mothership”. Every May for the last 3 years I have driven down to Tornado Alley to capture some amazing storms. This supercell held so much promise to drop a tornado but one small shift in the atmosphere and all that it produced was an extreme lightning show. Photo location: Broken Bow, Nebraska. (Photo and caption by Vanessa Neufeld/National Geographic Photo Contest)

Tracy Sarita celebrates the sunrise during the Burning Man 2015 “Carnival of Mirrors” arts and music festival in the Black Rock Desert of Nevada, September 3, 2015. Approximately 70,000 people from all over the world are gathering at the sold-out festival to spend a week in the remote desert to experience art, music and the unique community that develops. (Photo by Jim Urquhart/Reuters)