takeoff point for raids and attacks on shipping. Soviet war with Finland The last negotiations with Finland had been initiated by the Soviet side as part of its collective security policy in April 1938, and aimed to reach an understanding and to secure a favorable Finnish position in case of a German attack on the Soviet Union through Finnish territory, but this had proven futile due to the Finnish reluctance to break its neutrality, and negotiations ended in April 1939, shortly before Litvinov's dismissal. On October 13, 1939, new negotiations started in Moscow, and the Soviet Union (represented by Stalin, Molotov, and Vladimir Potyomkin) presented Finland with proposals including a mutual assistance pact, the lease of the military base of Hanko, and the cession of a 70 km-deep area on the Karelian Isthmus located immediately to the north of the city of Leningrad to the Soviet Union, in exchange for border lands further to the north. Finland, however, refused to accept the offer, withdrew from negotiations on November 7, 1939, and continued preparations for a possible Soviet invasion. 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 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. On December 14 the Soviet Union was expelled from the League of Nations for waging a war of aggression. After presiding over the disastrous start of the campaign, and a disproportionally heavy death toll of Red Army soldiers, Voroshilov was replaced by Semyon Timoshenko as the commander of the front on January 7, 1940 (and four months later as People's Commissar for Defense). In mid-February, 1940, Soviet troops finally managed to break through the Mannerheim Line, and Finland sought an armistice. The Moscow Peace Treaty was signed on March 12, 1940, and at