The selfie is the most popular photography trend of the internet today. It's gotten so popular, in fact, that even our beloved feline friends have started to catch on. I dare you to keep the smile off your face for this one!

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 model backstage during day 1 of Aspen Fashion Week 2011 on March 13, 2011 in Aspen, Colorado.

Alexis Ren seen at Focus Features Los Angeles Special Screening of “Nocturnal Animals” at Hammer Museum on Friday, November 11, 2016, in Los Angeles. (Photo by Eric Charbonneau/Invision for Focus Features/AP Images)

5-year-old Rina Kumari rubs her eye while cracking stones on the banks of Mahananda river in Siliguri, northeast India, March 5, 2005. Over 400 million people in India live below the internationally agreed poverty line (living on less than US $1 per day). According to estimates, several hundred thousand children work as labourers and beg on the streets in India. (Photo by Desmond Boylan/Reuters)

In this July 15, 2015 photo, Nepalese amputee victims Khendo Tamang, left, and Nirmala Pariyar, both 8, share a single pair of shoes at the Bir Trauma Center in Kathmandu, Nepal. After suffering serious leg wounds in Nepal's massive 2015 earthquake that killed and injured thousands, both girls were brought to the Bir Trauma Center in Kathmandu, to receive single leg amputations. Following their surgeries, Nirmala's relentless cheerfulness drew a still very depressed Khendo close and both found an inseparable friendship which has helped their emotional wounds heal. (Photo by Niranjan Shrestha/AP Photo)