Russia’s Supreme Court on Tuesday declared Ukraine’s Azov Regiment a terrorist organization banned in Russia, a designation that could expose Ukrainian prisoners of war held by Moscow to terrorism charges. Azov, which played a key role in the defense of Mariupol in southeastern Ukraine, has been repeatedly portrayed by Russian officials and state media as a Nazi formation allegedly committing atrocities against Ukrainian civilians. There is no evidence to support these claims. The Azov regiment is a unit of the National Guard of Ukraine. It was developed by a group called the Azov Battalion, created in 2014 as one of several volunteer brigades deployed to bolster Ukraine’s underfunded and embattled military in the fight against Russian-backed separatists in eastern Ukraine. The Azov Battalion drew its original fighters from far-right circles and drew criticism for some of its tactics. Its current members rejected accusations of nationalism and radicalism. Russia’s Prosecutor General’s office filed a motion to designate the regiment as a terrorist organization in May. Dozens of Azov fighters are being held captive in Moscow. Russian authorities have opened multiple criminal cases against them, accusing them of killing civilians. Last week, dozens of Ukrainian prisoners were killed in an explosion at a barracks in a penal colony in Olenivka, an eastern town controlled by pro-Russian separatists. Moscow and Kyiv have traded blame for the strike, with Kyiv saying Russia blew up the barracks to cover up torture of prisoners.