Thai emergency staff help the injured after the scene of an explosion near Erawan Shrine, central Bangkok, Thailand, 17 August 2015. An explosion in a busy commercial district in the Thai capital killed at least 15 people. Witnesses said the explosion happened around 7:15 pm (12:15 GMT) at the Rajprasong Intersection, a business area famous among tourists and locals for a revered Hindu shrine. (Photo by EPA/Stringer)

A female sniper of the Syrian Democratic Forces (SDF) monitors the area during a celebration at the iconic Al- Naim square in Raqa on October 19, 2017, after retaking the city from Islamic State (IS) group fighters. The SDF fighters flushed jihadist holdouts from Raqa' s main hospital and municipal stadium, wrapping up a more than four- month offensive against what used to be the inner sanctum of IS' s self- proclaimed “caliphate”. (Photo by Bulent Kilic/AFP Photo)

A Los Angeles County firefighter puts water a burning house in a wildfire in the Lake View Terrace area of Los Angeles Tuesday, December 5, 2017. Ferocious winds in Southern California have whipped up explosive wildfires, burning a psychiatric hospital and scores of other structures. Tens of thousands of people have been ordered evacuated. (Photo by Chris Carlson/AP Photo)

An Indian nomadic shepherd from the western Rajasthan state guides his flock of sheep through an access road in Greater Noida, outskirts of New Delhi, India, Tuesday, December 5, 2017. Looking for suitable pasture lands for grazing, shepherds migrate their flocks over extensive areas in the same state or to neighboring states in India. (Photo by R.S. Iyer/AP Photo)

In this photo taken on Sunday, January 14, 2018, Anastasia Gruzdeva, left, poses for selfie with her friends as the temperature dropped to about –50 degrees (–58 degrees Fahrenheit) in Yakutsk, Russia. Temperatures in the remote, diamond-rich Russian region of Yakutia have dropped to near-record lows, plunging to –67 degrees Centigrade (-88.6 degrees Fahrenheit) in some areas. (Photo by Sakhalife.ru Photo via AP Photo)

Soldiers stand guard in Maua square where a cotton candy vendor passes by in Rio de Janeiro, Brazil, Saturday, July 9, 2016, as security is deployed to get to know the areas they'll be patrolling during the Olympics. Roughly twice the security contingent at the London Olympics will be deployed during the August games in Rio, which are expected to draw thousands of foreigners to a city where armed muggings, stray bullets and turf wars between heavily armed drug gangs are routine. (Photo by Leo Correa/AP Photo)

A man carries an injured woman in a site hit by what activists said were airstrikes carried out by the Russian air force in the rebel-controlled area of Maaret al-Numan town in Idlib province, Syria January 9, 2016. At least 70 people died in what activists said where four vacuum bombs dropped by the Russian air force in the town of Maaret al-Numan; other air strikes where also carried out in the towns of Saraqib, Khan Sheikhoun and Maar Dabseh, in Idlib. (Photo by Khalil Ashawi/Reuters)