Once the political decision had been reached , the Imperial Japanese Army took over full control under Chief of Staff Yui Mitsue and extensive planning for the expedition was conducted . The Japanese eventually deployed 70,000 troops under command of general Kikuzo Otani – far more than any of the other Allied powers had anticipated . Furthermore , although the Allies had envisioned operations only in the vicinity of Vladivostok , within months Japanese forces had penetrated as far west as Lake Baikal and Buryatia , and by 1920 , '' zaibatsu '' such as Mitsubishi , Mitsui and others had opened offices in Vladivostok , Khabarovsk , Nikolayevsk-on-Amur and Chita , bringing with them over 50,000 civilian settlers . After the international coalition withdrew its forces , the Japanese Army stayed on . However , political opposition prevented the Army from annexing the resource-rich region . Japan continued to support White Movement leader Admiral Aleksandr Kolchak until his defeat and capture in 1920 , and also supported the regime of Ataman Semenov , who should take control under the buffer state in the future and whose unstable government collapsed by 1922 . In March and April 1922 , the Japanese Army repulsed large Bolshevik offensives against Vladivostok . On June 24 , 1922 , Japan announced that it would unilaterally withdraw from all of Russian territory by October , with the exception of northern Sakhalin island , which had been seized in retaliation for the Nikolayevsk incident of 1920 . On January 20 , 1925 , Soviet – Japanese Basic Convention was signed in Beijing . Following this convention , Japan undertook to withdraw their troops from northern Sakhalin by May 15 , 1925
Nikolayevsk incident
Nikolayevsk incident
Japanese intervention in Siberia