Yevgeny Roizman, a high-profile Russian dissident and former mayor of the city of Yekaterinburg, was detained Wednesday morning, purportedly over his public refusal to refer to Russia’s invasion of Ukraine as a “special military operation.”

“This case revolves around one phrase — ‘the invasion of Ukraine,’” Roizman told reporters as police escorted him from his apartment in a video posted to social media. Roizman was formally charged with discrediting the Russian armed forces via his popular YouTube channel, state-controlled Russian media outlet TASS reported, citing local law enforcement sources.

Moscow has long faced criticism for suppressing free speech and media, but has upped the ante with recent legislation that has effectively criminalized public criticism of or independent reporting on what Russia prefers to refer to as its “special military operation” in Ukraine.

Article 280.3 of the Russian Criminal Code prohibits “public actions aimed at discrediting” the Russian armed forces, stipulating punishments of up to three years in prison for violations. Article 207.3 prohibits the dissemination of “deliberately false information” about the country’s military, under threat of prison terms of up to 15 years. These amendments are phrased with characteristic vagueness, emboldening law enforcement authorities to crack down on a broad range of activities seen as unfriendly to the Kremlin’s narrative of the Ukraine conflict. To that end, Roizman’s arrest is among the latest iteration of the dozens of criminal cases and thousands of detentions Russian authorities have carried out in recent months.

According to TASS, Roizman has been formally charged under Article 280.3. His YouTube channel features impassioned criticism of Russia’s ongoing invasion, with no apparent effort to couch the conflict in Kremlin-friendly language.

Roizman rose to prominence in the late 1990s and early aughts for leading controversial efforts to combat Yekaterinburg’s then-burgeoning heroin problem. His initiative, A City Without Drugs, attracted praise for its effectiveness, and criticism for its draconian methods, which included holding drug users in veritable captivity and raids against suspected drug dealers. He ultimately moved into the political sphere, serving as an opposition lawmaker, and later as mayor of Yekaterinburg.