Many mosques were closed or torn down.[288] During the period of Joseph Stalin's leadership, Crimean Tatar, Chechen, Ingush, Balkar, Karachay, and Meskhetian Turk Muslims were victims of mass deportation. Though it principally targeted ethno-religious minorities, the deportations were officially based on alleged collaborationism[289] during the Nazi occupation of Crimea.[290] The deportation began on 17 May 1944 in all Crimean inhabited localities.