Boys walk near a damaged building in the rebel held besieged city of Douma, in the eastern Damascus suburb of Ghouta, Syria December 30, 2016. (Photo by Bassam Khabieh/Reuters)

Mariam, a 9-year-old girl, carries her brother as she stands with other children at an underground ancient cemetery in Jabal al-Zawiya in the southern countryside of Idlib November 26, 2014. Residents are using ancient caves and cemeteries as underground shelters to hide in during shelling from forces loyal to President Bashar al-Assad. Picture taken November 26, 2014. (Photo by Khalil Ashawi/Reuters)

A female army recruit attends a base training at the armored battalion in Setermoen, northern Norway on August 11, 2016. Norway has become the first NATO member to have compulsory conscription for women as well as men in the army. Recently, the first batch of army recruits joined the ranks in The Armored Battalion in the Norwegian Army located in Setermoen in northern Norway. (Photo by Kyrre Lien/AFP Photo)

Afghan militia men stand near to the dead body of a beheaded Islamic State group loyalist in the Achin district of Nangarhar province east of Kabul, Afghanistan, Sunday, December 27, 2015. An Afghan official says fighters for the Islamic State group and a militia controlled by a prominent lawmaker have beheaded a total of eight men in tit-for-tat revenge killings in the eastern border province of Nangarhar. (Photo by Mohammad Anwar Danishyar/AP Photo)

Residents observe a police officer take up position during an operation at the Mare slums complex in Rio de Janeiro March 25, 2014. The federal troops have taken control of security operations in Mare slums complex to help quell a surge in violent crime following attacks by drug traffickers on police posts in three slums on the north side of the city, government officials said. (Photo by Ricardo Moraes/Reuters)

Lamas dance during the “Tiaoqian” praying ceremony at the Youning Temple on February 8, 2009 in Huzhu County of Qinghai Province, China. (Photo by China Photos/Getty Images)

A motorized three-wheeled taxi carrying Muslim students drives past the Starbucks cafe where Thursday's attack occurred in Jakarta, Indonesia, on Friday, January 15, 2016. A day after attackers detonated bombs and engaged in gunbattles with police in the central part of Indonesia's capital, Jakarta tried to get itself back on track. (Photo by Dita Alangkara/AP Photo)

Mikhail Kalashnikov, the father of the world's most popular assault rifle, is handed an AK-74 November 23, 2002 in Izhevsk,1000 East km. from Moscow. November 23 marked the 55th anniversary of the release of the first Kalashnikov gun. According to the Moscow-based Center for Analysis of Strategic and Technologies some 70 million to 100 million Kalashnikovs have been built worldwide since 1947, compared about 7 million to Kalashnikov's Western rival the M-16 assault rifles. (Photo by Oleg Nikishin/Getty Images)