Timothy Snyder at Eurozine:
Perhaps above all, Auschwitz is resonant because it has come to stand for the depths of a fallen civilization. It is seen as evil, but also as modern. It reveals a tragic flaw. For this reason, its liberation by soldiers who seem to dialectically represent a healthy and victorious civilization is all the more poignant. If the Soviets freed Auschwitz, imply the civilizers, then they must have stood for values opposite to those of the Nazis who built it. Although many of the prisoners who awaited the Red Army at Auschwitz were not in fact Jewish, they have come to stand for those Jews who awaited the coming of the Soviets as their only chance for survival. The liberation of Auschwitz thus fits perfectly the civilizers' assumptions and literary needs, wedding as it does the emotionally irresistible force of the desperate hopes of Jewish survivors to the implicit notion that civilization itself has returned and triumphed.
This tempting literary move can only be made if prior references to Soviet power and policy are absent. Thus one can read a library of books about the Holocaust without learning that the Holocaust began in doubly-occupied lands where the German invasion of 1941 undid Soviet structures established after the Soviet occupation of 1939 in Poland or 1940 in the Baltics, that Soviet power was present everywhere the Holocaust took place, either immediately after or (usually) both before and after the mass murder of the Jews.
more here.