The 64-year-old, who described allegations of atrocities committed by soldiers in Ukraine, has been convicted of spreading "false information" in social media posts.
He has, among other things, called Putin the leader of a "terror state".
After Russia's large-scale invasion of Ukraine in February 2022, censorship and prosecutions for social media posts skyrocketed.
The man's lawyer says to OVD-info that the verdict was "very harsh", even considering the current situation with tough Russian laws being used to silence criticism of the Kremlin or the military.
The former physics and mathematics teacher was arrested at his home in Moscow in October 2023.
