A riot police blocks a street during a march near a meeting attended by the Secretary-General of Organization of American State Luis Almagro and leaders from various communities in Managua, Nicaragua, December 1, 2016. (Photo by Oswaldo Rivas/Reuters)

A model wears a creation for Miu Miu's Spring-Summer 2017 ready-to-wear fashion collection presented Wednesday, October 5, 2016 in Paris. (Photo by Francois Mori/AP Photo)

A woman looks towards part of an artwork called “Lichen! Libido! (London!) Chastity!” by Anthea Hamilton, one of the four artists shortlisted for the Turner Prize 2016, as it is displayed at the Tate Britain gallery in London, Monday, September 26, 2016. The Turner Prize aims to promote public debate around new developments in contemporary British art. (Photo by Kirsty Wigglesworth/AP Photo)

Members of the Albert Battery perform a gun salute during the Anzac Day dawn service held by the Currumbin RSL on the Gold Coast in Currumbin, Australia, 25 April 2016. The Anzac day marks the landing of the Australian and New Zealand Army Corps (Anzac) troops at Gallipoli in what is today Turkey during WWI. World War One, also called the Great War, according to official statistics cost more than 37 million military and civilian casualties between 1914 and 1918. (Photo by Glenn Hunt/EPA)

The Kung Fu Panda balloon is lifted before the 86th Annual Macy's Thanksgiving Day Parade November 22, 2012 in New York City. Macy's donated tickets and transportation to this year's Thanksgiving Day Parade to 5,000 people from neighborhoods hardest hit by Superstorm Sandy. (Photo by Charles Sykes/Associated Press)

Women in traditional costumes wait for a statue of the El Carmen Virgin to be carried into the sea during a procession in Malaga July 16, 2015. Many seaside towns celebrate the annual feast of the El Carmen Virgin, who is worshipped as the patron saint of sailors. (Photo by Jon Nazca/Reuters)

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.

A migrant carries his belongings as he arrives at the Beijing railway station to catch a train in Beijing, Friday, February 13, 2015. (Photo by Andy Wong/AP Photo)