A man from the Dominican Republic wears a devil mask while dancing in the street during Carnival celebrations in Panama City, Monday, February 16, 2015. (Photo by Arnulfo Franco/AP Photo)

The front wheels of a tractor, pulling a trailer overloaded with sugarcane, are seen lifted off the ground as it passes through the streets of Karor Lan Esan, Pakistan December 6, 2015. (Photo by Caren Firouz/Reuters)

A Puffing Billy steam train hauled by locomotive 14A crosses the Monbulk Creek trestle after leaving Belgrave station near Melbourne, October 20, 2014. While the discovery of steam power 200 years ago powered the Industrial Revolution, the world long ago shunted most steam trains onto the sidings of history. (Photo by Jason Reed/Reuters)

A Free Syrian Army (FSA) fighter reacts as he mourns near the body of his brother, who was an FSA fighter and died during an offensive against Islamic State fighters to take control of Qabasin town, on the outskirts of the northern Syrian town of al-Bab, Syria January 10, 2017. (Photo by Khalil Ashawi/Reuters)

Miss Universe contestant Desire Cordero, of Spain, poses for a photo after a news conference for contestants from Latin America and Spain, Monday, January 12, 2015, in Doral, Fla. The Miss Universe pageant will be held on January 25, in Miami. (Photo by Wilfredo Lee/AP Photo)

Passengers brave the strong winds as they wait for a bus, in Hong Kong, Monday, September 15, 2014. The Hong Kong Observatory issued the number 8 southeast storm signal, as Typhoon Kalmaegi edges closer to Hong Kong. (Photo by Kin Cheung/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.

Aerial view of the “Viracocha III”, a boat made only from the totora reed, as it is being prepared to cross the Pacific from Chile to Australia on an expected six-month journey, La Paz, Bolivia, October 19, 2016. An expedition in a boat made only of reeds crafted by indigenous Bolivians is getting ready to cross the Pacific from South America to Australia, in a fresh attempt to prove that ancient mariners were capable of making the journey. (Photo by David Mercado/Reuters)