Väinö Tanner (March 12, 1881 – April 19, 1966) was a pioneer and leader in the cooperative movement in Finland, and Prime Minister of Finland from 1926 to 1927. Tanner did not participate in the Finnish Civil War. When the war ended he became Finland's leading Social Democratic Party (SDP) politician, and a strong proponent of the parliamentary system. His main achievement was the rehabilitation of the SDP after the Civil War. Väinö Tanner served as Prime Minister (1926-1927), Minister of Finance (1937-1939), Foreign Minister (1939-1940), and after the Winter War Minister of Trade (1940-1942). This final move was due to Soviet pressure.