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 Chinese man wears a mask to protect against pollution as he waits at a red light while commuting to work in heavy smog on December 8, 2015 in Beijing, China. The Beijing government issued a 'red alert' for the first time since new standards were introduced earlier this year as the city and many parts of northern China were shrouded in heavy pollution. Levels of PM 2.5, considered the most hazardous, crossed 400 units in Beijing, lower than last week, but still nearly 20 times the acceptable standard set by the World Health Organization. The governments of more than 190 countries are meeting in Paris to set targets on reducing carbon emissions in an attempt to forge a new global agreement on climate change. (Photo by Kevin Frayer/Getty Images)

A Kashmiri girl holds her brother in the doorway of their home while watching protesters shout pro-freedom and anti-Indian slogans during mourning and protests held in downtown Srinagar on August 22, 2016, following the killing of teenager Irfan Ahmed by security forces. Teenager Irfan Ahmed was killed after he was hit in the chest by a teargas canister fired by Indian security forces to quell pro-freedom protests in the Kashmiri capital on August 21. More than 60 civilians have been killed in clashes between protesters and security forces, and thousands more injured in the worst violence to hit the Himalayan region since 201. Indian-administered Kashmir has been in the grip of almost daily anti-India protests and rolling curfews sparked by the killing on July 8 of a popular rebel leader, Burhan Wani, in a gunfight with government forces. (Photo by Tauseef Mustafa/AFP Photo)

In this July 15, 2015 photo, Nepalese amputee victims Khendo Tamang, left, and Nirmala Pariyar, both 8, share a single pair of shoes at the Bir Trauma Center in Kathmandu, Nepal. After suffering serious leg wounds in Nepal's massive 2015 earthquake that killed and injured thousands, both girls were brought to the Bir Trauma Center in Kathmandu, to receive single leg amputations. Following their surgeries, Nirmala's relentless cheerfulness drew a still very depressed Khendo close and both found an inseparable friendship which has helped their emotional wounds heal. (Photo by Niranjan Shrestha/AP Photo)

This undated handout image courtesy of the San Diego Zoo Wildlife Alliance shows “Pat”, a Pacific pocket mouse fondly named after actor Sir Patrick Stewart. A mouse named after “Star Trek” actor Patrick Stewart is officially the world's oldest in captivity, a US zoo has announced Pat the Pacific Pocket Mouse – the smallest species of mouse in North America – bagged the title when he hit nine years and 209 days old on February 8, 2023. (Photo by Ken Bohn/San Diego Zoo Wildlife Alliance via AFP Photo)

Igor Gavrilov, the main taxidermist of the Zoological centre at Tel Aviv University, works on a taxidermied animal, part of a collection which will be housed at the Steinhardt Museum of Natural History, a new Israeli natural history museum set to open next year in Tel Aviv, Israel June 8, 2016. Legions of insects, sea creatures and ancient fossils are lining up in a new museum shaped liked a giant Noah's Ark, telling the story of a crucial evolutionary byway across Israel. (Photo by Nir Elias/Reuters)

An Extinction Rebellion environmental activist couple getting married at an action site they are calling “The Beacon” on Westminster Bridge on October 7, 2019 in London, England. Primarily made up of London based activists the site is one of 12 situated around key Government locations in central London as actions are also predicted to occur in unto 70 cities around the world. The group aim to occupy the areas in central London for up to two weeks through non violent protest with an estimated 8 times as many people as their April protests which saw over 1,200 people arrested. (Photo by Ollie Millington/Getty Images)

A CIT guard carries his gun handgun while bringing a bag containing cash inside an armoured vehicle during a money collection in Johannesburg's CBD, on December 8, 2020. As the Christmas festive season approaches, cash-in-transit (CIT) companies are gearing up as they continue to be target of crime, with about 3000 money vans traveling daily nationwide. Despite the COVID-19 lockdown, there have been 260 cash-in-transit heist incidents in South Africa this year, with 19 CIT crew members killed. Cash-in-transit heists in the country are often military-style planned operations with criminals recurring to bomb making and assault rifles attacks. (Photo by Michele Spatari/AFP Photo)