The relations between the anarchists and the Bolsheviks worsened in Soviet Russia due to the suppression of movements like the Kronstadt rebellion and the Makhnovist movement. The Kronstadt rebellion (March 1921) was a key moment during which many libertarian and democratic leftists broke with the Bolsheviks, laying the foundations for the anti-Stalinst left. The American anti-Stalinist socialist Daniel Bell later said: