A member of the punk group p*ssy Riot is restrained by a member of the Cossack militia in Sochi, Russia, on Wednesday, February 19, 2014. Cossack militia attacked the p*ssy Riot punk group with horsewhips on Wednesday as the group tried to perform under a sign advertising the Sochi Olympics. The group had gathered to perform in a downtown Sochi restaurant, about 30km (21miles) from where the Winter Olympics are being held.They left the restaurant wearing bright dresses and ski masks and had only been performing for a few seconds when they were set upon by Cossacks. (Photo by Morry Gash/AP Photo)

A police officer jump ropes with a police dog at a police dog training base on July 11, 2011 in Beijing, China. The Police Dog Training Base was opened to a media visit to show the dogs skills to the public. (Photo by ChinaFotoPress/Getty Images)

Police clash with “Occupy Melbourne” protestors on October 21, 2011 in Melbourne, Australia. Protesters and riot police clashed in Melbourne today after police, acting on a Melbourne City Council eviction order, attempted to break up the crowd of hundreds that had been positioned in City Square for a week. (Photo by Mark Dadswell/Getty Images)

A woman cries after riot police dispersed demonstrators during protests to oust Narok county Governor Samuel Tunai in Narok, Kenya, January 26, 2015. At least seven people were injured on Monday in clashes between Kenyan police and protesters from the Maasai ethnic group who accuse a local governor of corrupt handling of tourism funds from the Maasai Mara game reserve, the Kenya Red Cross said. (Photo by Thomas Mukoya/Reuters)

Flowers are left at the scene of a hit and run following civil disturbances in the Winson Green area on August 11, 2011 in Birmingham, England. Police are continuing investigations after three people – reportedly trying to protect shops from rioting and looting in Dudley Road – were struck by a car. Police have so far arrested over 1,000 people following rioting which erupted over a four-day period across the UK. (Photo by Jeff J Mitchell/Getty Images)

An injured supporter of Kenyan opposition leader Raila Odinga receives assistance in Nairobi, Kenya on November 17, 2017. Kenyan police have used tear gas and water cannons to disperse supporters of opposition leader Raila Odinga who are trying to gather near the country's main airport and Uhuru park to welcome him back from an overseas trip. (Photo by Baz Ratner/Reuters)

A member of the Community Police of the FUSDEG (United Front for the Security and Development of the State of Guerrero) poses with a weapon during events to mark the first anniversary of the force's operations in Ocotito, January 23, 2015. Based on the traditional indigenous justice system, the Community Police is made up of volunteers from different communities of Guerrero, and was created in response to the spate of violence in several locations in the state. (Photo by Jorge Dan Lopez/Reuters)

A Polish Air Force MIG-29 fighter (R) and an Italian Air Force Eurofighter Typhoon fighter patrol over the Baltics during a NATO air policing mission from Zokniai air base near Siauliai, Lithuania February 10, 2015. (Photo by Ints Kalnins/Reuters)