The history of World War II is alive and kicking seven decades later, in a fierce debate over the moral high ground. On Tuesday, the 70th anniversary of the German invasion of Poland, Russian Prime Minister Vladimir Putin will speak in Gdansk, Poland, to defend the Soviet Union's policies vis-a-vis the war. This summer, Ukraine and the three Baltic states are rewriting history, comparing Josef Stalin to Adolf Hitler, calling the communist leader an aggressor rather than a liberator, and blaming the two dictators equally for WWII. "Suddenly, people are saying that Communist crimes are equal to Nazi crimes," explained Dr. Efraim Zuroff, a New York-born Israeli historian who specializes in Holocaust history and is the director of the Simon Wiesenthal Center's Jerusalem office. "They are saying that victims of Communism and Nazism are one and the same, and should be remembered together, and this is a dangerous idea," Zuroff said. The controversy began on August 23, 1939, when a non-aggression treaty was signed in Moscow by German foreign minister Joachim von Ribbentrop and Soviet foreign minister Vyacheslav Molotov. The pact secured Soviet neutrality and consequentially sealed the fate of Poland, which was invaded by the German army on September 1, 1939. In 1945, the secret protocol of the Molotov-Ribbentrop Pact was discovered in Nazi archives, but the Soviets continued to deny the treaty had ever existed, only changing their policy in 1989. Hitler and Stalin had agreed to split Eastern Europe into spheres of influence. Many Eastern Europeans say the Soviet Union did not come as a liberator when it defeated the Germans. Rather, the Soviets replaced the Nazi totalitarian regime with a Communist totalitarianism regime. Russian President Dmitry Medvedev rejects the parallel drawn between the German and the Soviet roles in WWII. Appearing on Russian television on Sunday, Medvedev said that to pronounce Nazi Germany and the Soviet Union "equally responsible for World War II [is] quite frankly... a flat-out lie." He reiterated that there could be no debate over "who started the war, which country killed people, and which country saved people, millions of people, and which country, ultimately, saved Europe." Putin's visit to Poland is meant to reaffirm the Soviet Union's role in WWII, according to Yury Ushakov, Putin's deputy chief of staff. "The goals of the upcoming visit are first, to counter attempts in the international context to revise the history of World War II, and second, to give a boost to Russian-Polish bilateral relations," explained Ushakov. Russians call WWII "The Great Patriot War," and according to Zuroff, see the Soviet victory over the Nazis as a national unifier. "Now Eastern Europeans are revising history and want to take that unifier away," he said. "Here we are 70 years post-war and all these questions are coming up, as if it is not 100 percent clear what happened," Zuroff exclaimed in disbelief. "Claiming Soviets acted [like the] Nazis goes against history," said Aviva Raz Shechter, director of the Foreign Ministry's Department for Combating Anti-Semitism. While expressing sympathy for those who suffered under totalitarianism regimes, Shechter said the Nazis had an ideology aimed at annihilating the Jews, while the Soviets did not. "The Holocaust is an unprecedented genocide, therefore there is no comparison, it cannot be trivialized." "The comparison comes because of outside commonalities such as horror, but basic motives and policies were completely different," explained Yehuda Bauer, academic adviser at Yad Vashem. Putin is expected to speak out strongly against revisionism and any comparison of Stalin to Hitler or of Soviets to Nazis. In addition, Russia is to release additional documents about Poland's role in WWII, from the secret achieves of Russia's foreign intelligence service, on Tuesday. The issues are not expected to be resolved anytime soon. "The real danger here is [to] the Jewish narrative of the Holocaust," Zuroff said.