A South Korean military vehicle drives past barricades at the military check point, near the Demilitarized zone (DMZ) separating South and North Korea on December 20, 2011 in Paju, South Korea. (Photo by Chung Sung-Jun/Getty Images)

South Korean soldiers participate in a winter river crossing operation in preparation for a possible North Korean attack on February 8, 2012 in Yeoju, South Korea. The Korean peninsula is the world's last Cold War frontier as stalinist North Korea and pro-western South Korea have been technically at war since the 1950-53 conflict. (Photo by Chung Sung-Jun/Getty Images)

Ukrainian artists assemble a barbecue grill in the shape of Moscow's Kremlin at their workshop in Kiev May 14, 2015. A group of Ukrainian artists are working on a project entitled “Mordor on Fire” where they create grills that are sold, and some donated to Ukrainian soldiers in the eastern conflict zone. (Photo by Gleb Garanich/Reuters)

An Afghan National Army (ANA) soldier assigned to the Mobile Strike Force Kandak fires a RPG-7 rocket-propelled grenade launcher during a live-fire exercise supervised by the Marines with the Mobile Strike Force Advisor Team on Camp Shorabak, Helmand province, Afghanistan, May 20, 2013. The Marines with the Mobile Strike Force Advisor Team instructed and mentored their ANA counterparts on how to properly utilize their weapons systems. (Photo by SSgt Ezekiel R. Kitandwe/RCT 7)

A young YPJ recruit (in pink) arrives to the training base for her first day in training near Derek City, Syria. The YPJ schedule is demanding and requires discipline – new soldiers in training get about 6 hours of sleep a night and wake up at 4 AM to begin exercising; afterwards, their day consists of a full schedule of drills and classroom lessons. Before joining the YPJ many of the girls had never participated in physical activity or sports before. (Photo by Erin Trieb/NBC News)

Members of a historical re-enactment group dressed as U.S. and Soviet Army soldiers take part in Elbe Day celebrations, in eastern German city of Torgau at the river Elbe, April 25, 2015. Elbe Day commemorates the encounter of the Allies 70 years ago, on the 25th of April 1945 when American and Soviet army units joined together on the destroyed bridge over the river Elbe. The photograph of the meaningful handshake made its way around the world and became a symbol of the near end of World War II in Europe. (Photo by Stefanie Loos/Reuters)

Mexicans dressed as French soldiers carry handcrafted guns, ahead of a reenactment of the battle of Puebla between Zacapoaxtla Indians and the French army during Cinco de Mayo celebrations in Mexico City, Tuesday, May 5, 2015. Monsalvo said he has been portraying Napoleon III in the annual neighborhood event for 28 years. Cinco de Mayo commemorates the victory of an ill-equipped Mexican army over French troops in Puebla on May 5, 1862. (Photo by Rebecca Blackwell/AP Photo)

A Yemeni soldier, pictured through a vehicle's windscreen, which was damaged by a bullet, gestures out of the window, in Marib, Yemen October 15, 2015. Marib is a city that is heavily armed even by the standards of Yemen, where the ready availability of weapons helped start civil war and is now preventing anyone coming out on top. Yemenis often say there are three guns for every person, a boast that has become an urgent concern in a country where the United Nations says the humanitarian situation is "critical". (Photo by Angus McDowall/Reuters)