Following World War II, at the insistence of Joseph Stalin during Tehran Conference confirmed (as not negotiable) at the Yalta Conference of 1945, Poland's borders were redrawn and Łuck – then again, Lutsk (Cyrillic: Луцьк) – was incorporated into the Ukrainian SSR of the Soviet Union. The remaining Polish population was expelled and resettled back to new Poland before the end of 1946. The Jewish community was never restored. The USSR officially ceased to exist on 31 December 1991.