In this picture taken Thursday, April 14, 2016, a Syrian man carries a carpet as walk through a devastated part of the town of Palmyra as families load their belongings onto a bus in the central Homs province, Syria. Thousands of residents of this ancient town who fled Islamic State rule are returning briefly to check on their homes and salvage what they can – some carpets, blankets, a fridge or a few family mementos. There is no water or electricity in the town, and it will be at least few months before anyone can return to stay. (Photo by Hassan Ammar/AP Photo)

A protester peeks out from behind of a banner as supporters of anti-immigrant activists and nationalists march to protest against the Polish governments decision to accept migrants from Syria and North Africa, in Warsaw, Poland, September12, 2015. EU President Donald Tusk said he would call a special summit on the migration crisis if the bloc's interior ministers do not display “solidarity and unity” at emergency talks on 14 September about the thousands of migrants streaming into Europe. (Photo by Jacek Turczyk/EPA)

Syrian boys play with plastic guns on the first day of the Muslim religious festival of Eid al-Adha in al-Dana in Syria's rebel-controlled Idlib region, near the border with Turkey, on August 11, 2019. Muslims across the world are celebrating the first day of the Feast of Sacrifice, which marks the end of the hajj pilgrimage to Mecca and commemorates prophet Abraham's sacrifice of a lamb after God spared Ishmael, his son. (Photo by Aaref Watad/AFP Photo)

A bomb-laden Su-25 jet at the Hmeimim air base in December 2015. Russia's lease agreement obliged Assad’s military to safeguard the perimeter of the Hmeimim base, while giving Moscow legal jurisdiction over the facilities inside. Negotiating perimeter protection from Syria’s new rulers will be vital for the Russian bases in an era of wire-controlled drones immune to jamming. (Photo by AP Photo)

Armed Syrian Turkmen villagers are seen near the northern Syrian village of Yamadi, near the Turkish-Syrian border, Syria, November 24, 2015. Turkey shot down a Russian warplane near the Syrian border on Tuesday saying it had repeatedly violated its air space, one of the most serious publicly acknowledged clashes between a NATO member country and Russia for half a century. (Photo by Reuters/Stringer)

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)

Mohammad, a 13-year-old fighter from the “Free Syrian Army”, plays with a cat in Aleppo's Bustan al-Basha district, Syria October 28, 2013. Mohammad joined the Free Syrian Army after his father died during clashes with the Syrian regime. The gun he is using was his father's. (Photo by Molhem Barakat/Reuters)

A boy wearing a Lebanon's Hezbollah military outfit and carrying a toy gun walks during the funeral of three Hezbollah fighters who were killed while fighting alongside Syrian army forces in Syria in Nabatieh town, southern Lebanon, October 27, 2015. The fighters names are Hussein Hassan Shreifie, Ali al-Akbar Mohamad Khashfeh and Mohamad Saeed Fawaz. (Photo by Ali Hashisho/Reuters)