In 1918, Japan joined the Allies in a joint intervention into the Russian Civil War in support of the White movement. Ōtani was appointed head of the Japanese expeditionary force with Yui Mitsue as the Chief of Staff. The Vladivostok Expeditionary Force was 60,000 men strong, comprising three divisions including the 12th Division and the 5th Division. On 12 August, Japanese forces departed from Tokyo Station for Hiroshima, where they were to board ships destined for Vladivostok. Following Vladivostok's occupation Otani became the formal commander of the Allied Siberian Intervention. In April 1920, Ōtani ordered the Allied troops to cut off eastern Transbaikal from the Bolshevik-controlled Far Eastern Republic thus creating the Chita holdup.