The Ribbentrop-Molotov Pact - sometimes referred to as the German-Soviet Pact - was signed on this day 83 years ago.
In a previous Radio Poland article, British historian Roger Moorhouse is quoted as emphasizing that the Pact has not received the attention it deserves in the "West".
The American historian Ian Ona Johnson says in an interview with the Polish Press Agency that the groundwork for the Pact was being developed even before Hitler came to power.
Johnson, a professor at Notre Dame University in the USA, explains that the German High Command and the Soviet leadership shared a bitterness at the reemergence of an independent Poland - a symbol of German defeat in World War I and Russian defeat against Poland.
"The Generals of the German High Command wanted to prepare for a war of revenge to overturn the results of the First World War, and the only country inclined to cooperate was the Soviet Union, also isolated at the time."
Talks between the two pariah states had already begun during the Poland-Bolshevik war, during which Germany gave discreet support to the Soviets.
Johnson's book, The Faustian Bargain: Secret Soviet-German Military Cooperation in the Interwar Period, is forthcoming with Oxford University Press.
Sources: PAP, University of Notre Dame website