September 2 had the dubious distinction of marking the 80th anniversary of the German invasion of Poland and the start of World War II. Leaders around the globe marked the event in various ways.
An arguably even more critical event has received less attention — the second invasion of Poland on September 17, 1939 – this time by the Soviet Union.
By some estimates over 800,000 Soviet troops participated in this invasion with military operations lasting for twenty days. To avoid fighting a two-front war, Stalin’s order did not go into effect until one day after the Soviet–Japanese ceasefire, ending the border skirmish at Nomonhan ( a decisive Soviet victory).
Polish forces already overwhelmed in their struggle with Germany were no match for the Soviet aggressors.
The division of Poland between Moscow and Berlin was envisioned via a secret clause in the Molotov–Ribbentrop Pact of August 23, 1939, though the actual Soviet invasion created new realities on the ground. For example, Lithuania was supposed to be controlled by Germany under the plan envisioned in the Molotov-Ribbentrop Pact. Instead, the region fell under Soviet control as the Soviet Union used the war in Poland as a pretext to demand basing rights from the Baltic states leading to their eventual annexation.
This second invasion of Poland is too often overlooked. In 2014, then U.S. President Barrack Obama had the dubious distinction of announcing a plan to abandon the development of a missile defense system in Eastern Europe on the 75th anniversary of the Soviet Invasion of Poland.