Today, September 17, marks the 70th anniversary of the invasion of eastern Poland by the Soviet Union. Long before Soviet Russia "liberated" Poland from Nazi German occupation in 1945, the Soviets had designs on Poland and in 1939 signed a friendship pact with Germany, officially called the Treaty of Non-Aggression, in August 1939. The so-called "Ribbentrop-Molotov Pact" secretly agreed to carve up Poland between its two powerful neighbours. On September 1, 1939, Poland was invaded from the west by Nazi Germany. As part of the deal, the Soviet Union invaded Poland from the east on September 17 and World War II was underway. It would later lead to the arrest of Polish officers and their murder by the Soviets in Katyn. In Gdansk, Poland, earlier this month at the 70th anniversary of the start of World War II, Russian premier Vladimir Putin admitted it was a "mistake" for Russia to back Germany in Poland - Russia would itself be attacked by double-crossing Nazi Germany in 1941, an act of aggression which finally made Soviet leader Jozef Stalin side with the western allies against Germany. For details about Andrzej Wajda's film "Katyn" please CLICK HERE