Visitors dressed in superhero costumes attend the Paris Comics Expo at the Parc Floral in Paris, France, April 15, 2016. (Photo by Charles Platiau/Reuters)

Team McLaren Mercedes drivers Lewis Hamilton (L) and Jenson Button unveil the new MP-27 Formula 1 car at the McLaren technology centre on February 1, 2012 in Woking, England. (Photo by Mark Thompson/Getty Images)

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.

Amundsen-Scott South Pole Station experiences months of darkness. The sun dips below the horizon on March 21, after which follows several weeks of twilight before complete darkness results. Photo taken on June 25, 2009. (National Science Foundation/Jeremy Johnson)

Members of the Dominican Armed Forces participate in a commemorative act on the 170th anniversary of national independence at the esplanade of Santo Domingo, on February 27, 2014. (Photo by Orlando Barria/EPA)

Two cats watch a mouse walking on the pavement in Kuwait City on March 8,2017. (Photo by Yasser Al-Zayyat/AFP Photo)

New Orleans police officers try to keep their heads down as they move in on a Black Panther headquarters during an exchange of gunfire in New Orleans on September 15, 1970. The shootout occurred as police moved in to make arrests on Tuesday morning following a series of incidents. (Photo by Jack Thornell/AP Photo)

A belly dancer performs in a talent show in early morning ceremonies for Groundhog Day on February 2, 2018 in Punxsutawney, Pennsylvania. Punxsutawney Phil, the weather-forecasting groundhog, emerged from his burrow in Pennsylvania on Friday, saw his shadow and predicted six more weeks of winter, despite his rival Staten Island Chuck in New York predicting an early spring. (Photo by Brett Carlsen/Getty Images)