More than 2,000 people were arrested on Sunday at anti-war protests in 48 cities across Russia, a protest group said, as people defied the authorities to show their anger over Russia's invasion of Ukraine.
More than 5,500 people have been arrested at various anti-war protests since the invasion began on Thursday, according to the OVD-Info monitor, which has documented crackdowns on Russia's opposition for years.
In Moscow, the riot police often outnumbered protesters, some of whom carried hand-written placards with peace signs and anti-war slogans in Russian and Ukrainian. Some wore masks with the word Enough emblazoned in the front.
Hundreds of anti-war protesters gathered in downtown Saint Petersburg and chanted arms outside the upmarket Gostiny Dvor department store.
Sunday s protests coincided with the seventh anniversary of the murder of opposition politician Boris Nemtsov.
A witness said in Moscow that some of the arrests took place at an improvised memorial just outside the Kremlin at the site where Nemtsov was shot. One of the demonstrators shouted as he was being dragged away by the police.
Nemtsov was a prominent critic of President Vladimir Putin, Russia annexation of Crimea in 2014 and Moscow's support for pro-Russian separatists in Ukraine, which ultimately led to what Putin labeled as a special operation to protect the two separatist regions, although his troops are fighting in wider Ukraine.
Ukraine s Western allies have slapped unprecedented sanctions in response to Russia's land, sea and air invasion.
On Sunday, Putin ordered his military command to put nuclear-armed forces on high alert as Ukrainian fighters who were defending the city of Kharkiv said they had repelled an attack by invading Russian troops.
Hundreds of thousands of people across Europe marched in protest against Russia's invasion on Sunday, with 100,000 people protesting in solidarity with Ukraine in Berlin.