The Russian government threatened the activists, warning them that they could face arrest.
Hundreds of protesters across dozens of cities in Russia were detained by authorities on Thursday.
Anti-war protesters in Russia quickly took to the streets following Russian President Vladimir Putin's invasion of UkraineProtesters march with a banner that reads: "Ukraine - Peace, Russia - Freedom," in Moscow, Russia, Thursday, Feb. 24, 2022.
AP Photo/Dmitry Serebryakov
Some activists were met with hostility by Russian authorities who hauled them awayAuthorities detain demonstrators in Moscow, Russia, Thursday, Feb. 24, 2022.
AP Photo/Dmitry Serebryakov
More than 1,000 anti-war protesters have already been detained in dozens of cities across Russia, according to protest-monitoring group OVD-InfoA police officer detains a woman during a gathering in St. Petersburg, Russia, Thursday, Feb. 24, 2022.
AP Photo/Dmitri Lovetsky
Russia's Investigative Committee warned citizens not to take part in the "unauthorized" protests "associated with the tense foreign political situation."An activist is detained during an action against Russia's attack on Ukraine in Moscow, Russia, Thursday, Feb. 24, 2022.
AP Photo/Dmitry Serebryakov
But that did not stop demonstrators from turning out in dozens of Russian cities, including St. Petersburg and NovosibirskCops detain a demonstrator during a gathering in St. Petersburg, Russia, Thursday, Feb. 24, 2022.
AP Photo/Dmitri Lovetsky
Russia launched an all-out war against Ukraine early Thursday, prompting the backlashPolice officer detain a woman during an action against Russia's attack on Ukraine in Moscow, Russia, Thursday, Feb. 24, 2022.
AP Photo/Dmitry Serebryakov
Russia's Investigative Committee said that people should be aware of the "negative legal consequences of these actions," which it said includes criminal liabilityA protester is detained in central St. Petersburg on February 24, 2022.
ERGEI MIKHAILICHENKO/AFP via Getty Images
The anti-war protests grew larger and larger as time went on ThursdayAuthorities detain a demonstrator during an anti-war protest in Pushkin Square in central Moscow.
Sergei Savostyanov\TASS via Getty Images
Hundreds of anti-war activists gathered in Putin's hometown of St. PetersburgA demonstrator holding a placard reading "No to war" protests against Russia's invasion of Ukraine in central Saint Petersburg on February 24, 2022.
Photo by SERGEI MIKHAILICHENKO/AFP via Getty Images
