Demonstrators made barricades during clashes with police following a protest condemning the arrest of rap artist Pablo Hasél in Barcelona, Spain, Thursday, February 18, 2021. The imprisonment of a rap artist for his music praising terrorist violence and insulting the Spanish monarchy has set off a powder keg of pent-up rage this week in Spain. (Photo by Emilio Morenatti/AP Photo)

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 simulated casualty is evacuated during an emergency services exercise at the disused Aldwych underground station on February 22, 2012 in London, England. Operation Forward Defensive aims to test the response to a terrorist incident on the London Underground network during the 2012 Olympic Games. (Photo by Peter Macdiarmid/Getty Images)

Local men help a wounded woman after a mortar attack by the Ukrainian army of the center of Donetsk, Ukraine, 14 August 2014. Reports state that ten local people where wounded and one killed after the mortar attack. (Photo by Sergei Ilnitsky/EPA)

Iraqi forces gather during an operation to attack Islamic State militants in Mosul, Iraq, October 21, 2016. (Photo by Reuters/Stringer)

A couple kiss in front of a barricade set by demonstrators during clashes with police following a protest condemning the arrest of rap singer Pablo Hasél in Barcelona, Spain, Thursday, February 18, 2021. Protests over the imprisonment of a rapper convicted for insulting the Spanish monarchy and praising terrorist violence have morphed for the third night in a row into rioting. Pablo Hasél began this week to serve a 9-month sentence in a northeastern prison. (Photo by Emilio Morenatti/AP Photo)

A member of the pro-government “red shirt” movement attacks a Buddhist monk outside the National Anti-Corruption Commission office in Nonthaburi province, on the outskirts of Bangkok March 24, 2014. Members of the movement attacked the monk after he shouted complaints to the group blocking a road near the National Anti-Corruption Commission. (Photo by Chaiwat Subprasom/Reuters)

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)