Estonia joined the League of Nations in 1921. Attempts to establish a larger alliance together with Finland, Poland, and Latvia failed, with only a mutual defence pact being signed with Latvia in 1923, and later was followed up with the Baltic Entente of 1934. In the 1930s, Estonia also engaged in secret military co-operation with Finland. Non-aggression pacts were signed with the Soviet Union in 1932, and with Germany in 1939. In 1939, Estonia declared neutrality, but this proved futile in World War II.