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 Houthi follower with fake blood on his clothes lies on the ground to represent a victim as others perform a war dance during a ceremony marking the first anniversary of the Houthi movement's takeover of Yemen's capital Sanaa September 21, 2015. (Photo by Khaled Abdullah/Reuters)

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)

Migrants ride on top of a northern bound train toward the US-Mexico border in Juchitan, southern Mexico, Monday, April 29, 2013. Migrants crossing Mexico to get to the U.S. have increasingly become targets of criminal gangs who kidnap them to obtain ransom money. (Photo by Eduardo Verdugo/AP Photo)

Girls play in the makeshift refugee camp at the northern Greek border point of Idomeni, Greece, Thursday, March 17, 2016. Leaders of the EU's 28 divided nations reconvene in Brussels in hopes of ironing out disagreements on a proposed agreement with Turkey in the migrants crisis. (Photo by Vadim Ghirda/AP Photo)

Howard Jackson, a Liberian migrant, poses for a portrait in the Andalusian capital of Seville, southern Spain March 7, 2016. Jackson escaped civil war and spent three years crossing Africa before reaching Spain. Dressed up in one of his more than 200 costumes, from Peter Pan to Little Red Riding Hood, he is a well-known figure at an intersection entering the Spanish city of Seville where he has sold tissues to motorists for over a decade. Jackson is studying law and wants to become a judge. (Photo by Marcelo del Pozo/Reuters)

Models and Caroline Scheufele, Artistic Director and Co-President of Chopard (C) pose during a photocall ahead of the Chopard Gold Party during the 68th Cannes Film Festival in Cannes, southern France, May 18, 2015. (Photo by Yves Herman/Reuters)

An officer of a Libyan anti-illegal immigrants unit conducts an early morning raid on migrants at hideout in Tripoli, Libya October 13, 2015. Libyan security forces charged with curbing illegal migration raided a hide-out for illegal migrants in Tripoli on Tuesday. (Photo by Hani Amara/Reuters)