Riot police clash with demonstrators protesting against proposed pension reforms outside the Congress in Buenos Aires on December 18, 2017. Protesters angry at proposed pension and welfare reforms attacked police close to Argentina's congress building in Buenos Aires on Monday, the second protest in a week to turn violent. Activists lobbed stones, bottles and firecrackers at police as huge crowds demonstrated against pension reforms proposed by the center-right government of President Mauricio Macri. (Photo by Eitan Abramovich/AFP Photo)

A police officer sprinkles colored powder onto a police dog at Nepal's Central Police Dog Training School during a dog worship day as part of the Diwali festival, also known as Tihar Festival, in Kathmandu, Nepal, 10 November 2015. The Tihar festival is the second major festival for Nepalese Hindus and this year is held from 10 November 2015. (Photo by Narendra Shrestha/EPA)

A mob attacks a female police officer accused of shooting a protester in the Buterere neighborhood of Bujumbura, Burundi, May 12, 2015. Protesters opposed to the president's decision to run for a third term chased, beat and stoned the woman, who was later handed back to the police. (Photo by Goran Tomasevic/Reuters)

St Louis County police officers arrest an anti-police demonstrator in Ferguson, Missouri August 10, 2015. Dozens of protesters were arrested on Monday afternoon after blocking rush-hour traffic on Interstate 70 a few miles (km) from Ferguson, Missouri, during demonstrations over the police shooting of an unarmed black man a year ago, according to a Reuters witness. (Photo by Lucas Jackson/Reuters)

Northeastern girls getting commando training at the Delhi Police Training Centre, Jharoda Kalan on September 4, 2017 in New Delhi, India. For the first time ever, Delhi Police are providing commando training to 40 young women from the Northeast. Once the commando training is over, these girls will be a part of the «Parakram Vans», an initiative taken by Delhi Police against terrorism. (Photo by Manoj Verma/Hindustan Times via Getty Images)

Two Girls who managed to evade the police walk away as police on foot and horseback push back to te curd at Park Row, In New York on April 26, 1960, A milling throng of more than 1,000 High students who storned city hall in a Demonstration supporting teachers wage demands. (Photo by AP Photo)

A counter-protester grabs the flag of a pro-police demonstrator during a rally, following weeks of protests against racial inequality in the aftermath of the death in Minneapolis police custody of George Floyd, in Boston, Massachusetts, U.S. June 27, 2020. (Photo by Brian Snyder/Reuters)

A police officer stands at a police cordon near the scene of a terror attack in London, U.K., on Sunday, June 4, 2017. A van swerved into Saturday-night crowds on London Bridge, before three men got out and went on a stabbing rampage through nearby bars. (Photo by Luke MacGregor/Bloomberg)