The early Soviet leaders publicly denounced anti-Semitism, William Korey wrote: "Anti-Jewish discrimination had become an integral part of Soviet state policy ever since the late thirties." Efforts were made by Soviet authorities to contain anti-Jewish bigotry notably during the Russian civil war, whenever the Red Army units perpetrated pogroms, as well as during the Soviet-Polish War of 1919–1920 at Baranovichi. Only a small number of pogroms were attributed to the Red Army, with the vast majority of the 'collectively violent' acts in the period having been committed by anti-Communist and nationalist forces.