People look at a man, who residents said was killed by al Qaeda militants, hanging on a bridge in Yemen's southeastern city of Mukalla June 17, 2015. Al Qaeda militants in Yemen killed two alleged Saudi spies, residents said, accusing them of planting tracking devices which enabled the assassination of the group's leader in a suspected U.S. drone strike. (Photo by Reuters/Stringer)

This file photo provided on Sunday February 15, 2015 by the Syrian anti-government activist group Aleppo Media Center (AMC), which has been authenticated based on its contents and other AP reporting, shows Syrian rebels firing locally made shells against the Syrian government forces, in Aleppo, Syria. (Photo by AP Photo/Aleppo Media Center)

A man dressed as the “Star Wars” character Darth Vader sits on a bench in central Lviv, Ukraine, November 24, 2016. (Photo by Gleb Garanich/Reuters)

First graders of a cadet's lyceum attend a ceremony to mark the start of the new school year in Kiev, Ukraine, September 1, 2015. September 1 marks the start of a new academic year for students in Ukraine.(Photo by Valentyn Ogirenko/Reuters)

Rebel fighters from the Ahrar al-Sham Islamic Movement fire a heavy machine gun during what they said was an offensive to take the northwestern city of Idlib March 24, 2015. (Photo by Khalil Ashawi/Reuters)

Iraqi government forces are seen near the Falahat village west of Fallujah on June 27, 2016. Iraqi forces took the Islamic State group's last positions in the city of Fallujah on June 26, establishing full control over one of the jihadists' most emblematic bastions after a month-long operation. (Photo by Moadh Al-Dulaimi/AFP Photo)

In this January 31, 2014 file photo released by the United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA), shows residents of the besieged Palestinian camp of Yarmouk, queuing to receive food supplies, in Damascus, Syria. That year, the U.N. was able to deliver food to about five percent of people in besieged areas including Yarmouk, while today estimates show the organization is reaching less than one percent. (Photo by UNRWA via AP Photo)

The painted nails of a Kurdish Peshmerga female fighter are seen as she takes up a position during combat skills training before being deployed to fight Islamic State militants, at their military camp in Sulaimaniya, northern Iraq September 18, 2014. (Photo by Ahmed Jadallah/Reuters)