Early in the morning of 24 August 1939, the Soviet Union and Nazi Germany signed a 10-year non-aggression pact, called the Molotov–Ribbentrop Pact. The pact contained a secret protocol, revealed only after Germany's defeat in 1945, according to which the states of Northern and Eastern Europe were divided into German and Soviet "spheres of influence". In the north, Latvia, Finland and Estonia were assigned to the Soviet sphere. A week later, on 1 September 1939, Germany and on 17 September, the Soviet Union invaded Poland.