Spanish soldiers of the 7th Airborne Light Infantry Brigade “Galicia” fire a howitzer Light Gun L118 during maneuvers with other units in preparation to NATO's Very High Readiness Joint Task Force (VJTF) in Zaragoza, Spain, April 19, 2016. (Photo by Javier Cebollada/EPA)

India's Border Security Force (BSF) soldiers ride their camels during a rehearsal for the “Beating the Retreat” ceremony in New Delhi, India, January 27, 2016. The ceremony symbolises retreat after a day on the battlefield, and marks the official end of the Indian Republic Day celebrations. It is held every year on January 29. (Photo by Anindito Mukherjee/Reuters)

Soldiers from Japan's Ground Self Defense Force come ashore in amphibious assault vehicle as they train alongside U.S. Marines during the bilateral annual Iron Fist military training exercise in Camp Pendleton, California February 26, 2016. (Photo by Mike Blake/Reuters)

Pfc. Sebastian Rodriguez, machine gunner, Weapons Platoon, Lima Company, 3rd Battalion, 3rd Marine Regiment, Marine Rotational Force – Darwin, fires an M240 machine gun during a night squad-attack exercise, here, May 22, 2013. (Photo by Sgt. Sarah Fiocco/U.S. Marines)

A policeman aims his weapon in Istanbul, Turkey July 16, 2016. Members of Turkey's armed forces said they had taken control of the country Friday as explosions, gunfire and a reported air battle between loyalist forces and coup supporters erupted in the capital. President Erdogan remained defiant and called on people to take to the streets to show support for his embattled government. (Photo by Kemal Aslan/Reuters)

Leidi, a member of the 51st Front of the Revolutionary Armed Forces of Colombia (FARC), poses for a picture at a camp in Cordillera Oriental, Colombia, August 16, 2016. A peace deal will end half a century of war and allow the rebels to reintegrate into Colombian society. (Photo by John Vizcaino/Reuters)

Two F-15E Strike Eagles wait to receive fuel from a KC-135R Stratotanker during exercise Red Flag 15-1 on their way to Nellis Air Force Base, Nev., Jauary 23, 2015. The F-15s are assigned to the 4th Fighter Wing. U.S. (Photo by Airman 1st Class Aaron J. Jenne/Reuters)

Armed forces veteran Frank Simpson at the Portico library being camouflaged by body artist Carolyn Roper in Manchester, UK on May 16, 2016 as part of the #CountThemIn campaign launched on Monday by the Royal British Legion. (Photo by Jon Super/Royal British Legion/PA Wire)