In this Tuesday, August 2, 2016 photo released by Xinhua News Agency, people stand on a platform as the Transit Elevated Bus TEB-1 conducting a test run after it unveiled in Qinhuangdao, north China's Hebei Province. The 72-feet long and 25-feet wide Transit Elevated Bus (TEB) powered by electricity can carry more than hundreds passengers, is designed to go over the normal traffic to help ease traffic congestion without having to dig new tunnels or build elevated rail tracks. (Photo by Luo Xiaoguang/Xinhua via AP Photo)

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.

Soldiers stand guard in Maua square where a cotton candy vendor passes by in Rio de Janeiro, Brazil, Saturday, July 9, 2016, as security is deployed to get to know the areas they'll be patrolling during the Olympics. Roughly twice the security contingent at the London Olympics will be deployed during the August games in Rio, which are expected to draw thousands of foreigners to a city where armed muggings, stray bullets and turf wars between heavily armed drug gangs are routine. (Photo by Leo Correa/AP Photo)

An actor performs during the show “Paris de Nuit” in Santiago, Chile, 20 September 2016. The show is a combination of cabaret and circus, produced by the Recirquel Contemporary Circus Company from Budapest, and will be performed at the Mapocho Cultural station from 20 to 25 September. (Photo by Mario Ruiz/EPA)

A participant blows on yellow powder held in her hand during a Holi Party before the Gay Pride Parade in Barcelona on July 9, 2016. (Photo by Lluis Gene/AFP Photo)

Women play soccer as the Tungurahua volcano spews a column of ash during an eruption in Huambalo, Ecuador, Saturday, March 5, 2016. Tungurahua is 16,480 feet (5,023 meters) high and has been active since 1999. (Photo by Dolores Ochoa/AP Photo)

People stand around a leopard with its head stuck in a vessel in Rajsamand district of Rajasthan state, India, Wednesday, September 30, 2015. The leopard's head got stuck when it attempted to drink water from the pot, according to news reports. Forest officials tranquilized the animal and sawed off the vessel later in the day. (Photo by Kabir Jethi/AP Photo)

Myanmar revellers take part in celebrations on the fifth and last day marking Thingyan, a water festival which brings in the country's new year, in Yangon on April 16, 2016. The Buddhist festival of water pouring symbolizes spiritual cleansing and begin the new year free from worldly impurities with celebrants devoting the four days of Thingyan in merry making of water dousing until the eve of new year. (Photo by Romeo Gacad/AFP Photo)