Vladimir Kara-Murza, a prominent critic of the Kremlin and opponent of Russias invasion of Ukraine, was arrested in Moscow on Monday.

Kara-Murza was detained by Russian law enforcement and sentenced to 15 days in jail for disobeying police, reports The Guardian . It was not clear if the arrest was linked to the prominent activists recent critiques of Russias deadly war on Ukraine.

Earlier that day, CNN posted a video interview in which Kara-Murza called out the Kremlins regime of murderers for their history of poisoning and killing political opponents . He has also written columns in The Washington Post condemning Russias actions in Ukraine.

Kara-Murza himself has said he was previously poisoned twice by Kremlin actors.

Early on Tuesday, Kara-Murzas wife, Evgenia, demanded his release in a tweet: Twice have the Russian authorities tried to kill my husband for advocating for sanctions against thieves and murderers, and now they want to throw him in prison for calling their bloody war a WAR.

Amid Russias weekslong, deadly attack on Ukraine, the Kremlin has cracked down severely on journalists in the country.

Last month, just days into Russias invasion of Ukraine, Russian President Vladimir Putin signed a law criminalizing news reports that contradict the Kremlins version of its attack on Ukraine.