Political map of Russia & the former Soviet Union 01 July 1922 (Japanese Withdrawal): The Japanese had been involved in Siberia (Japan during the Siberian Intervention) for almost 4 years. Their intervention had achieved little and cost a great deal. Now also under pressure from the U.S., they decided to withdraw. By October 25, the last Japanese troops had left Vladivostok and the communists took over. With the Japanese gone, the Far Eastern Republic (Far Eastern Republic) had served its purpose and was annexed by Soviet Russia on November 15. However, Japan still controlled North Sakhalin and continued covert backing of the Whites in the northeast.