 On 30 November 1939 , Soviet forces invaded Finland with 21 divisions , totaling some 450 @,@ 000 men , and bombed Helsinki . Later the Finnish statesman J. K. Paasikivi commented that the Soviet attack without a declaration of war violated three different non @-@ aggression pacts : the Treaty of Tartu signed in 1920 , the non @-@ aggression pact between Finland and the Soviet Union signed in 1932 and again in 1934 , and also the Covenant of the League of Nations , which the Soviet Union signed in 1934 . C.G.E. Mannerheim was appointed Commander @-@ in @-@ Chief of the Finnish Defence Forces after the Soviet attack . In further reshuffling , the Finnish government named Risto Ryti as the new prime minister and Väinö Tanner as foreign minister . 
