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 bombing civilian boroughs of Helsinki. On December 1, 1939, the puppet socialist government of the Finnish Democratic Republic was established under the auspices of the Soviet Union in the border town of Terijoki.