Men work at a makeshift oil refinery site in Marchmarin town, southern countryside of Idlib, Syria December 16, 2015. The refinery site, owned by Yousef Ayoub, 34, has been active for 4 months. Ayoub says that he gets the crude oil from Islamic State-controlled areas in Deir al-Zor province and Iraq. The price for a barrel of crude oil varies and is controlled by the Islamic State, but it is currently at $44 dollars per barrel, he said. (Photo by Khalil Ashawi/Reuters)

A heat-stressed koala waits as a resident pours water on its back on December 19, 2015 in Adelaide, Australia. Adelaide is experiencing an extreme heatwave, with temperatures reaching over 40 degrees for five consecutive days. (Photo by Morne de Klerk/Getty Images)

An Afghan policeman stands guard in front of a French restaurant “Le Jardin” after a suicide attack in Kabul, Afghanistan January 2, 2016. A suicide attack on a French restaurant in the Afghan capital Kabul on Friday killed a 12-year-old boy and wounded more than a dozen other people, officials said. (Photo by Mohammad Ismail/Reuters)

A monkey is led by its trainer Qi Defang during training for a circus in Suzhou, Anhui province, November 29, 2014. Suzhou is known as the hometown of circus troupes in China and has more than 300 circus troupes. (Photo by William Hong/Reuters)

A member of the United States Naval Academy freshman class crawls through trenches at the wet and sandy station during the annual Sea Trials training exercise at the U.S. Naval Academy on May 13, 2014 in Annapolis, Maryland. For 14 hours, the United States Naval Academy freshman class, also known as Plebes, worked as a team to complete many grueling physical and mental challenges that help prepare them for real-world experiences and reinforce leadership, bonds, trust, and teamwork. Of the challenges, they endured: a two-mile regimental run, ground fights, water tactics, aquatics challenges, and survival skills, amongst many others. (Photo by Patrick Smith/Getty Images)

An unknown number of guns are being built with the mechanisms, causing problems for the police and ATF officials. Photo: An ATF agent holds a generic unfinished receiver, back, and one that has been manufactured, front, at an ATF field office in Washington, on May 06, 2014. The ATF is trying to crack down on the trade in the makeshift guns by targeting shops and individuals who offer to turn the unfinished receivers into functional pieces for firearms. (Photo by Bill O'Leary/The Washington Post)

Wearing traditional Belarus costumes girls jump over a bonfire as they celebrate the Ivan Kupala night, an ancient heathen holiday, held in the countryside near the town of Turov, some 260 km southwest of the capital Minsk, on July 6, 2014. People celebrate Kupala Night with bonfires that last throughout the night with some leaping over the flames as it is believed that the act of jumping over the bonfire cleanses people of illness and bad luck. (Photo by Viktor Drachev/AFP Photo)