A girl uses her mobile phone during the evening at the National Park in Khartoum, Sudan, April 24, 2015. (Photo by Mohamed Nureldin Abdallah/Reuters)

Senator Barack Obama (D-IL) (R) stands in front of Senator Hillary Clinton (D-NY) as they arrive for U.S. President George W. Bush's annual State of the Union speech to a joint session of Congress at the U.S. Capitol in Washington in this January 23, 2007 file photo. Hillary Clinton announced her second run for the presidency on April 12, 2015 starting her campaign as the Democrats' best hope of fending off a crowded field of lesser-known Republican rivals and retaining the White House. (Photo by Larry Downing/Reuters)

A man poses in front of a portrait of late Chinese Chairman Mao Zedong during the opening of an exhibition of Mao related art in Beijing, China, September 8, 2016. (Photo by Thomas Peter/Reuters)

Firefighters pull a pig as they try to rescue it from a well at a pig farm in Huanghua township of Leqing, Zhejiang province, China, April 25, 2014. Seven local firefighters successfully rescued the 300 kg (661 lbs) pig, local media reported. (Photo by Reuters/China Daily)

In this January 24, 2017 photo, boxer Idamerys Moreno wraps a bandage on her hand before a training session at a sports center in Havana, Cuba. Boxing has long been an athletic engine for Cuba, which has won 72 Olympic medals in that category but women are not allowed to box. (Photo by Ramon Espinosa/AP Photo)

Runners gather at the start line for the annual “Santa Speedo Run”, a charity race through the streets of the Back Bay neighborhood of Boston. (Photo by Gretchen Ertl/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.