Supporters of Russian opposition leader Alexey Navalny organized protests across Russia Tuesday, with the largest scheduled for Moscow’s Manezhnaya Square. Authorities vowed to respond with force after organizers did not seek permits for the gatherings.

Authorities also warned four online news outlets about “publishing materials containing public incitements to change the constitutional order,” according to Radio Free Europe. Meanwhile, state-owned outlets like RT and Itar-Tass ignored the protests or published critical reports.

UPDATE: 1:07 p.m. EST: Nearly 200 people have been arrested at the demonstrations, according to OVDinfo.org.

UPDATE 11:50 a.m. EST: Police arrested a dozen or so protesters, causing a dozens others to disperse.

UPDATE 11:27 a.m. EST: Navalny was swiftly arrested by a group of police as he and his supporters marched to Manezhnaya Square. Police have not yet moved in on the larger protest group. There appears to be between 100-200 protesters gathered.

Navalny, the most prominent opposition voice in Russian politics, was given a suspended sentence Tuesday in a Moscow court, while his brother Oleg was given 3.5 years for his alleged role in the theft of around $500,000 from a French company. The case was considered to be largely politically motivated and a way to silence critics of Russian President Vladimir Putin and his government. Navalny decried the decision to sentence his brother.

“This time they're purposefully destroying, torturing and tormenting the relatives of people who are their political opponents,” he said, according to Bloomberg. “I call on everyone to go to the streets until the authorities, who are grabbing and torturing innocent people, are ousted.”

Navalny, who has been under house arrest since February, will remain so until the end of his suspended sentence. If he breaks the law in that time, he could be jailed for that term. He will reportedly attend the protests in Moscow on Tuesday, which would break his house arrest.

The sentencing was scheduled to take place in mid-January, but the court moved it up in what many call an attempt to sneak the verdict in just before the New Year holiday to avoid protests. The U.S. Embassy in Moscow urged Americans to stay away “due to the possibility of large crowds and violence.”

Alexey Navalny escaped his house arrest and is moving towards manezhnaya square pic.twitter.com/JfGPve0kFM — Feldman (@EvgenyFeldman) December 30, 2014

â€” Carl Schreck (@CarlSchreck) December 30, 2014

US Embassy in Moscow warns Americans about possible violence at tonight's planned @navalny protests near Kremlin. pic.twitter.com/N16Tkm9073 â€” Carl Schreck (@CarlSchreck) December 30, 2014

Protesters set up a group chat on Firechat to organize the Moscow protest. The peer-to-peer chat service is able to function if local Internet is turned off, although authorities have not said whether that is a possibility. Many of the messages in the chat decry Putin and link to this live-stream video of Manezhnaya Square:

The protests were in part organized by Pussy Riot, the contentious anti-Putin punk group that has caused controversy worldwide for radical tactics, including an anti-government protest in a church that earned two members two-year prison sentences that were later struck down ahead of the Olympics in Sochi earlier this year. The group made a video urging Russians to demonstrate against the Navalny ruling: