U.S. soldiers from the 3rd Cavalry Regiment take part in an artillery exercise on forward operating base Gamberi in the Laghman province of Afghanistan December 24, 2014. (Photo by Lucas Jackson/Reuters)
A soldier shares a tender moment with his girlfriend while other soldiers rest during a rehearsal of a military parade a few days before the Independence Day in Kiev, Ukraine, Monday, August 22, 2016. Ukraine to mark the 25th anniversary of the Independence Day on August 24. (Photo by Efrem Lukatsky/AP Photo)
In this Friday, February 27, 2015 photo, an Israeli high-school senior preparing to join the Israeli military later this year participates in a privately run training camp for military combat fitness near Yakum, central Israel. With a mandatory three-year military service looming after graduation, teenage boys, and increasingly girls too, are gearing up for the draft, getting into shape and trying to improve their chances of acceptance into elite combat units. (Photo by Oded Balilty/AP Photo)
BAZ-69092-012 special wheeled chassis. Exhibition of military vehicles at Bronnitsy test range (a town in Moscow Oblast, Russia, located 54.5 kilometers (33.9 mi) southeast of central Moscow). Juny 10, 2011. (Photo by Vitaly Kuzmin)
A girl has her helmet adjusted on the top of a tank during the Children's Day celebration at a military facility in Bangkok, Thailand January 9, 2016. Army barracks opened their doors to children to interact with their weapons and vehicles as part of the celebration. (Photo by Jorge Silva/Reuters)
A Palestinian student jumps through a fire ring during a military-style show at a school in Rafah in the southern Gaza Strip March 28, 2016. (Photo by Ibraheem Abu Mustafa/Reuters)
A female honor guard has lipstick applied as they prepare for an official welcoming ceremony outside the Great Hall of the People in Beijing, China on June 11, 2014. (Photo by Jason Lee/Reuters)
Russian Mi-28N from the Berkuty (Golden Eagles) helicopter display team fly in formation during the “Aviadarts” military aviation competition at the Dubrovichi range near Ryazan, Russia, August 2, 2015. The aircraft started dipping down due to back propeller failure and crashed, killing one of two pilots, according to a Reuters photographer and official representatives of the competition. The aviation contest is part of the International Army Games, which are held in Russia from the 1st till the 15th of August with participants from 17 countries, according to organizers. (Photo by Maxim Shemetov/Reuters)