Russian policemen prepare to block a street prior to an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. Police have established a heavy presence at the Moscow mayor's office ahead of an expected protest rally and several opposition figures have been detained. (Photo by Pavel Golovkin/AP Photo)





Law enforcement officers detain a participant of a rally calling for opposition candidates to be registered for elections to Moscow City Duma, the capital's regional parliament, in Moscow, July 27. 2019. (Photo by Maxim Shemetov/Reuters)





A law enforcement officer stands guard during a rally calling for opposition candidates to be registered for elections to Moscow City Duma, the capital's regional parliament, in Moscow, July 27, 2019. The detentions came around a protest to demand that opposition members be allowed to run in a local election. Authorities had declared it illegal and sought to block participation, but several thousand people turned up anyway in one of the longest and most determined protests of recent years. (Photo by Maxim Shemetov/Reuters)





Law enforcement officers detain a participant of a rally calling for opposition candidates to be registered for elections to Moscow City Duma, the capital's regional parliament, in Moscow, Russia July 27, 2019. Russian police rounded up more than 1,000 people in Moscow on Saturday in one of the biggest crackdowns of recent times against an increasingly defiant opposition decrying President Vladimir Putin s tight grip on power. (Photo by Shamil Zhumatov/Reuters)





Protesters attempt to remove fences during a rally calling for opposition candidates to be registered for elections to Moscow City Duma, the capital's regional parliament, in Moscow, July 27, 2019. (Photo by Tatyana Makeyeva/Reuters)





A woman talks with a law enforcement officer during a rally calling for opposition candidates to be registered for elections to Moscow City Duma, the capital's regional parliament, in Moscow, July 27, 2019. (Photo by Tatyana Makeyeva/Reuters)





Law enforcement officers clash with protesters during a rally calling for opposition candidates to be registered for elections to Moscow City Duma, the capital's regional parliament, in Moscow, July 27, 2019. (Photo by Maxim Shemetov/Reuters)





Law enforcement officers detain protesters during a rally calling for opposition candidates to be registered for elections to Moscow City Duma, the capital's regional parliament, in Moscow, July 27, 2019. (Photo by Maxim Shemetov/Reuters)





Rosguardia (National Guard) soldiers block a street prior to an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. (Photo by Pavel Golovkin/AP Photo)





Police officers detain a woman prior to an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. OVD-Info, an organization that monitors political arrests, said about 50 people had been detained by 1:30 p.m. Saturday (1030 GMT), a half-hour before the protest against the exclusion of opposition figures from the ballot for city council elections was to start. (Photo by Alexander Zemlianichenko/AP Photo)





Police officers detain a man during an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. Russian police on Saturday began arresting people outside the Moscow mayor's office ahead of an election protest demanding that opposition candidates be allowed to run for the Moscow city council. (Photo by Alexander Zemlianichenko/AP Photo)





Police officers detain people during an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. Russian police on Saturday began arresting people outside the Moscow mayor's office ahead of an election protest demanding that opposition candidates be allowed to run for the Moscow city council. (Photo by Alexander Zemlianichenko/AP Photo)





Police officers detain a woman during an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. Russian police are wrestling with demonstrators and have arrested hundreds in central Moscow during a protest demanding that opposition candidates be allowed to run for the Moscow city council. (Photo by Pavel Golovkin/AP Photo)





Police officer helps his comrade after he was injured in clashes with protesters during an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. (Photo by Pavel Golovkin/AP Photo)





Protesters clash with police during an unsanctioned rally in the center of Moscow, Russia, Saturday, July 27, 2019. (Photo by Pavel Golovkin/AP Photo)





A law enforcement officer detains a participant of a rally calling for opposition candidates to be registered for elections to Moscow City Duma, the capital's regional parliament, in Moscow, Russia on July 27, 2019. (Photo by Shamil Zhumatov/Reuters)