Russian left-leaning activist Sergei Udaltsov faced trial on Monday, charged with “justifying terrorism” in online activities, a crime that could result in a prison term of up to seven years.

“The trial is underway. The charges have been presented. Sergei has entered a plea of not guilty,” his attorney, Dmitry Agranovsky, told the state news agency RIA Novosti.

Details of the specific accusations remain undisclosed; however, Udaltsov has stated that he is alleged to have shown support online for Marxist activists accused of establishing a “terrorist group” in Ufa.

The 48-year-old Udaltsov is being tried at Moscow’s Second Western District Military Court. He has been in pre-trial detention since January 2024.

A significant opposition figure during the anti-Kremlin protests in 2011-2012, Udaltsov was incarcerated in 2014 for orchestrating what authorities deemed “mass riots,” resulting in a three-year prison sentence.

Despite being a known critic of Putin, Udaltsov has expressed support for Russia’s invasion of Ukraine, claiming his opposition to Putin is based on a “patriotic” perspective.

An outspoken admirer of Soviet leader Josef Stalin, Udaltsov has long advocated for the revival of the Soviet Union.

In a 2012 interview with the independent outlet TV Rain, he remarked that “Stalin wasn’t a criminal” and has frequently been arrested and fined for organizing memorial events on Stalin’s birthday.