Russian police detain a protester at a demonstration against President Vladimir Putin in St.Petersburg, Russia, Saturday, May 5, 2018. (Photo by Dmitri Lovetsky/AP Photo)

Ayah, 37, weeps as she is embraced by a police officer during a demonstration against the Danish face veil ban in Copenhagen, Denmark, August 1, 2018. (Photo by Andrew Kelly/Reuters)

North Korean traffic police women chat next to a residential building while off duty Tuesday, October 18, 2016, in Pyongyang, North Korea. (Photo by Wong Maye-E/AP Photo)

A refugee sits in front of a Greek riot police cordon during a protest at the Greek-Macedonian border, near the Greek village of Idomeni, March 1, 2016. (Photo by Alexandros Avramidis/Reuters)

A police officer lies on the street after being run over by a bus during a protest against the increase in the price of public transport in San Cristobal, Venezuela March 29, 2016. (Photo by Carlos Eduardo Ramirez/Reuters)

A student protester throws a stone against a riot police vehicle during a demonstration to demand changes in the education system in Santiago, Chile, April 21, 2016. (Photo by Ivan Alvarado/Reuters)

A drunk student is sick on the street watched by a police officer following a night of heavy drinking during freshers week in United Kingdom on November 28, 2007. (Photo by Matthew Horwood/Alamy Stock Photo)

A demonstrator kicks a riot police vehicle during an unauthorized march called by the Chilean student federations to protest against government's education reform, in Santiago, Chile July 5, 2016. (Photo by Ivan Alvarado/Reuters)