シベリア出兵
In August 1918, Ushijima was assigned to the staff of the Japanese Expeditionary Force based at Vladivostok during the Siberian Intervention against Bolshevik forces during the Russian Civil War, where his duty was to coordinate the dispatch of troops and to arrange transportation of supplies. He was promoted to captain later that year. On his return to Japan, he was awarded the Order of the Golden Kite, 5th class.