Boys walk near a damaged building in the rebel held besieged city of Douma, in the eastern Damascus suburb of Ghouta, Syria December 30, 2016. (Photo by Bassam Khabieh/Reuters)

A man and a woman both wounded by what locals say was recent shelling by Ukrainian forces, react as they sit in an ambulance in Donetsk August 23, 2014. (Photo by Maxim Shemetov/Reuters)

Soviet Army soldiers sit on their tanks in front of the Czechoslovak Radio station building in central Prague during the first day of Soviet-led invasion to then Czechoslovakia on August 21, 1968. (Photo by Libor Hajsky/Reuters)

A marine aims an RPG-7, a portable rocket- propelled grenade launcher, during military exercises conducted by the Russian Pacific Fleet' s naval infantry unit at the Bamburovo firing range on February 2, 2017. The drills are a part of preparations for the Suvorov Attack and Sniper Line army competitions. (Photo by Yuri Smityuk/TASS)

An Iraqi Kurdish Peshmerga takes part in a graduation ceremony at the Zakho military academy in the Iraqi Kurdish town of Zakho, some 500 kilometres north of Baghdad, on January 30, 2018. (Photo by Safin Hamed/AFP Photo)

A Syrian rebel walks past Sham 2, a homemade armored vehicle, in Bishqatin, Syria, on December 8, 2012. From a distance it looks rather like a big rusty metal box but closer inspection reveals a homemade armored vehicle waiting to be deployed. Sham II, named after ancient Syria, is built from the chassis of a car and touted by rebels as “100 percent made in Syria”. (Photo by Herve Bar/AFP Photo)

A “Free Syrian Army” fighter in the Bustan Pasha neighborhood of Aleppo, Syria, August 21, 2013. (Photo by James Lawler Duggan)

A man covered with dust sits on a street following a reported air strike by Syrian government forces in the rebel-held neighbourhood of Sukkari in the northern city of Aleppo on May 30, 2016. (Photo by Baraa Al-Halabi/AFP Photo)