 Complete the following phrase:  On November 26, the Soviet Union staged the shelling of Mainila near the border, accused Finnish troops of the provocation and requesting their withdrawal. In turn, on November 27 Finland requested a withdrawal of troops of both nations from the border area. On November 28, the Soviet Union denounced the 1932 Soviet-Finnish Non-Aggression Pact, and on November 29 broke off diplomatic relations with Finland. On November 30, 1939, forces of the USSR under the command of Kliment Voroshilov attacked Finland in what became known as the Winter War, starting with the invasion of Finnish Karelia and 