Thousands of Polish Jews migrated, were deported or later evacuated to Central or Eastern Soviet Union and many of them survived the Holocaust. Some of them died however because of hard conditions, Soviet repressions or in result of Ukraininian nationalist's violence. Two Bund leaders, Wiktor Alter and Henryk Erlich were executed in December 1941 in Moscow as alleged agents of Nazi Germany. Some Jews joined the Polish Communist Army (Józef Różański, Włodzimierz Brus) or Union of Polish Patriots (Julia Brystiger) and returned to Poland in 1944, others were allowed to leave the Soviet Union after the war or around 1956 (Lew Rywin).