The years from 23 August 1939, the German–Soviet Non-Aggression Pact to 5 March 1953, Stalin's death, were the worst in the history of Soviet Jews, and were correctly called ‘the black years’, years of ‘physical and spiritual holocaust’, of ‘anxiety and despair’.

As individuals and as a national minority, the Jews were the object of an intense hatred, both under the Nazi regime which sought their extermination, and under the Stalinist regime which regarded them with suspicion and hatred. Caught between two totalitarian regimes at the peak of their power, the Jews had to fight for survival. The period can be divided into three sub-periods: 1939–41, the years of German-Soviet friendship; 1941–5, the war years; and 1945–53, the post-war period.

In the first, relatively short, period, the Jewish population in the Soviet Union underwent far-reaching changes in its socio-economic composition, with the new western frontier increasing its number from three to five million. There was a certain softening in the official antinationalist line and a halt to the dissolution of Jewish cultural institutions. Moreover, the influence of Jews from Poland, Romania, and the Baltic States, with their strong sense of Jewish identity, was of immeasurable importance in reinvigorating Jewish national feeling, which had begun to fade under the impact of Sovietization in the late 1930s.

Then, in the war years, in the shadow of the Holocaust, and despite Jewish heroism in the army, the partisan forces and the ghettos, an equivocal official policy was pursued regarding the Jewish minority.