Serbian police officers of the Special Anti-Terrorist Unit pose for a picture in their base outside Belgrade October 8, 2014. When the killing of an unarmed black teenager by a white policeman in Ferguson, Missouri, in August sparked sometimes violent protests, the response of police in camouflage gear and armoured vehicles wielding stun grenades and assault rifles seemed more like a combat operation than a public order measure. Some U.S. police departments have recently acquired U.S. military-surplus hardware from wars abroad, but there are many law enforcers around the world whose rules of engagement also allow the use of lethal force with relatively few restrictions. But for every regulation that gives police wide scope to use firearms, there is another code that sharply limits their use. In Serbia, police may use measures ranging from batons to special vehicles, water cannon and tear gas on groups of people who have gathered illegally and are behaving in a way that is violent or could cause violence, but they may use firearms only when life is endangered. (Photo by Marko Djurica/Reuters)

A fragment of a Koran manuscript is seen in the library at the University of Birmingham in Britain July 22, 2015. A British university said on Wednesday that fragments of a Koran manuscript found in its library were from one of the oldest surviving copies of the Islamic text in the world, possibly written by someone who might have known Prophet Mohammad. Radiocarbon dating indicated that the parchment folios held by the University of Birmingham in central England were at least 1,370 years old, which would make them one of the earliest written forms of the Islamic holy book in existence. (Photo by Peter Nicholls/Reuters)

A jogger runs on the bank of Donaukanal channel in central Vienna, Austria, September 5, 2016. (Photo by Heinz-Peter Bader/Reuters)

Each year Nikon Small World recognizes the excellence of photography taken under the microscope. The contest showcases the beauty and complexity of life. Anyone interested in microscopy and photography can enter the contest and in its 42nd year, Nikon Small World received 2,000 entries from 70 countries. Here: 11th Place; Scales of a butterfly wing underside (Vanessa atalanta). (Photo by Francis Sneyers/Nikon's Small World 2016)

Shell, which is the replica of the biggest detonated Soviet nuclear bomb AN-602 (Tsar-Bomb), is on display in Moscow, Russia, August 31, 2015. The shell is part of an exhibition organized by the state nuclear corporation Rosatom. (Photo by Maxim Zmeyev/Reuters)

Hollywood actress Malin Akerman helps King Digital Entertainment set the Guinness World Record for the World's Largest Hammock to celebrate the launch of its new game Paradise Bay on Wednesday, September 2, 2015, in Jersey City, N.J. (Photo by Charles Sykes/Invision for King World Entertainment/AP Images)

This adventurous husband and wife who are PAID to explore the world will give you a serious case of wanderlust. The Best Job in the World author, Ben Southall from Petersfield, Hampshire and his stunning Australian wife, Sophee are the definition of couple goals. The loved up pair with a taste for the extreme, launched, The Best Life in the World, last year with an incredible 34,000 mile journey from Singapore to London – in a mustard Land Rover. Here: Ben Southall’s wife, Sophee, takes a moment in Turkmenistan . (Photo by Ben Southall/Caters News Agency)

A girl walks in front of a graffiti painted on the wall of a house located inside the 15th-century complex built by Mameluk Sultan al-Ashraf Qaitbey, in Cairo's City of the Dead, Egypt February 13, 2017. (Photo by Amr Abdallah Dalsh/Reuters)