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.

An actor plays an injured passer-by during Exercise Strong Tower, the scene of a mock terror attack at a disused underground station in central London, Britain June 30, 2015. London police held their biggest-ever terrorism drill on Tuesday, pitting the emergency services against a group of marauding attackers, nearly 10 years since four young British Islamists killed 52 people in suicide bombings on London's transport network in July 2005. (Photo by Peter Nicholls/Reuters)

A local resident stumbles as he wades through flood water on a residential street in Carlisle, Britain December 6, 2015. British police have declared a major incident in northern England after prolonged heavy rain caused widespread flooding and forced emergency services to evacuate residents from their homes. (Photo by Phil Noble/Reuters)

Actor George Clooney is arrested with his father Nick Clooney (2R) during a demonstration outside the Embassy of Sudan March 16, 2012 in Washington, DC. United to End Genocide, the Enough Campaign and Amnesty International held a rally to call on the United States and world leaders to stop the violence in South Sudan and prevent hundreds of thousands of people from starving. (Photo by Win McNamee/Getty Images)

Meatball, a bulldog, poses in a tuxedo at the Tompkins Square Halloween Dog Parade on October 20, 2012 in New York City. Hundreds of dog owners festooned their pets for the annual event, the largest of its kind in the United States. (Photo by John Moore)

Canadian soldiers from the Royal 22nd Regiment take up a position during a non-combative extraction operation in a simulated village as part of Rim of the Pacific (RIMPAC) 2016 exercise held at Camp Pendleton, California United States, July 11, 2016. (Photo by Mike Blake/Reuters)

2016 Rio Olympics, Gymnastics training, Rio Olympic Arena, Rio de Janeiro, Brazil on August 4, 2016. Close up of the feet of Rebecca Downie (GBR) of United Kingdom as she trains on the beam. (Photo by Dylan Martinez/Reuters)

Korean Air flight attendants photograph a therapy dog dressed in a Superman Halloween costume, as part of a program to de-stress passengers at the international boarding gate area of LAX airport in Los Angeles, California, United States, October 27, 2015. (Photo by Lucy Nicholson/Reuters)