A protester dressed as a clown holds an umbrella over a Swiss police officer on a motorbike during a May Day demonstration in Zurich, Switzerland on May 1, 2017. (Photo by Arnd Wiegmann/Reuters)

A Ukrainian man stands in protest in front of gunmen in unmarked uniforms as they stand guard in Balaklava, on the outskirts of Sevastopol, Ukraine, Saturday, March 1, 2014. (Photo by Andrew Lubimov/AP Photo)

Police take part in a role play exercise as they clear a protest on top of a train during training on March 6, 2012 in Oxenhope, England. A new team of specialist officers set up to deal with searches and policing at a height, such as on top of a train, undergo training exercise in Oxenhope, West Yorkshire. (Photo by Bethany Clarke/Getty Images)

A protester reacts as police use water cannon during a demonstration to demand changes in the Chilean education system in Santiago, Chile June 25, 2015. (Photo by Ueslei Marcelino/Reuters)

A pro-independence protester sits in front of Catalonia's regional parliament as lawmakers vote inside, in Barcelona, January 16, 2014. (Photo by Albert Gea/Reuters)

Anti-Heathrow expansion activists walk through the “Grow Heathrow” protest camp in the village of Sipson near to Heathrow Airport, west London Britain December 7, 2015. (Photo by Peter Nicholls/Reuters)

A supporter of U.S. President Donald Trump fights with counter protesters during a march in response to various pro-Trump rallies held throughout D.C., in Washington, U.S., December 12, 2020. (Photo by Leah Millis/Reuters)

An injured demonstrator receives aid during a protest against a lockdown planned for the capital this weekend to halt the spread of the coronavirus disease (COVID-19) in Belgrade, Serbia on July 7, 2020. (Photo by Marko Djurica/Reuters)