A tribesman loyal to the Houthi movement carries his rifle as he leaves a gathering held to show support for the group, in Yemen's capital Sanaa December 15, 2015. (Photo by Khaled Abdullah/Reuters)

Photographers work on the red carpet after the screening of the film “Mad Max: Fury Road” out of competition at the 68th Cannes Film Festival in Cannes, southern France, May 14, 2015. (Photo by Regis Duvignau/Reuters)

A tribal fighter loyal to Yemen's government stands in Al Khurais village of Nihm district east of the capital Sanaa January 11, 2016. (Photo by Ali Owidha/Reuters)

A migrant tries to restrain her tent from strong winds in a makeshift camp for refugees and migrants at the Greek-Macedonian border near the village of Idomeni, Greece, March 24, 2016. (Photo by Alexandros Avramidis/Reuters)

People stand by a damaged car at a train station at a makeshift camp for migrants and refugees at the Greek-Macedonian border near the village of Idomeni, Greece, May 10, 2016. (Photo by Marko Djurica/Reuters)

A Syrian refugee girl cries as she walks through a rainstorm towards Greece's border with Macedonia, near the Greek village of Idomeni, September 10, 2015. Most of the people flooding into Europe are refes fleeing violence and persecution in their home countries who have a legal right to seek asylum, the United Nations said on Tuesday. (Photo by Yannis Behrakis/Reuters)

A Macedonian police officer hits a stranded migrant attempting to cross the Greek-Macedonian border, near Gevgelija, Macedonia December 2, 2015. Picture taken from the Greek side of the border. (Photo by Alexandros Avramidis/Reuters)

A pro-Russian rebel shows his t-shirt depicting Russian President Vladimir Putin at a checkpoint in the village of Chornukhyne near the town of Debaltseve, north-east from Donetsk, March 12, 2015. (Photo by Marko Djurica/Reuters)