Members of the U.S. Army 173rd Airborne Brigade stand at attention as a Ukrainian folk dance group performs at the opening ceremony of the “Rapid Trident” NATO military exercises on September 15, 2014 near Yavorov, Ukraine. The two-week exercises include participating units from a variety of NATO and NATO-associate countries as well as Ukrainian troops. Meanwhile fighting between pro-Russian separatists and Ukrainian armed foces has flared again in eastern Ukraine in a battle for the control of Donetsk airport despite the tenuous ceasefire. (Photo by Sean Gallup/Getty Images)

Girls look at a penitent taking part in “Nuestro Senor Atado a la Columna, Maria Santisima de la Paz y San Juan Evangelista” Holy Week procession in Arcos de la Frontera, Spain, Tuesday, March 31, 2015. Hundreds of processions take place throughout Spain during the Easter Holy Week. (Photo by Daniel Ochoa de Olza/AP Photo)

A devotee carrying an idol of the Hindu god Ganesh, the deity of prosperity, jumps into the Sabarmati river to immerse the idol during the 10-day-long Ganesh Chaturthi festival in Ahmedabad, India, September 11, 2016. (Photo by Amit Dave/Reuters)

A group of men play Myanmar's traditional sport of chinlone in Naypyitaw, Myanmar, Friday, November 18, 2016. (Photo by Aung Shine Oo/AP Photo)

Actors Ma Sichun (L) and Zhou Dongyu pose backstage after both won the Best Leading Actress award for their movie “Soul Mate” at the 53rd Golden Horse Film Awards in Taipei, Taiwan November 26, 2016. (Photo by Tyrone Siu/Reuters)

Syrian government troops patrol the newly captured al- Sakhour neighbourhood in the eastern part of the northern city of Aleppo on December 7, 2016 Rebels in Aleppo called for a five- day truce and the evacuation of civilians Wednesday after losing more than three quarters of their territory including the Old City to a Syrian army offensive. (Photo by George Ourfalian/AFP Photo)

Members of the Iraqi Army fire towards Islamic State militant positions at the south of Mosul, Iraq December 10, 2016. (Photo by Alaa Al-Marjani/Reuters)

A military instructor helps a boy to shoot a rifle with blanks at a weapon exhibition during a military show in St.Petersburg, Russia, Sunday, January 17, 2016. (Photo by Dmitry Lovetsky/AP Photo)