Empire of Japan

====Siberian Intervention====
[[File:Major General Graves, U.S.A., Gen. Otani, Japanese Army, and Staff, Vladivostok, Siberia., ca. 1918 - ca. 1919 - NARA - 533738.jpg|thumb|Commanding Officers and Chiefs of Staff of the Allied Military Mission to [[Siberia]], [[Vladivostok]] during the [[Siberian intervention|Allied intervention]]]]

{{Main|Allied intervention in the Russian Civil War|Siberian Intervention|Japanese intervention in Siberia}}

After the fall of the Tsarist regime and the later provisional regime in 1917, the new [[Bolshevik]] [[Russian Soviet Federative Socialist Republic|government]] signed a separate peace [[Treaty of Brest-Litovsk|treaty]] with Germany. After this, various factions that succeeded the Russian Empire fought amongst themselves in [[Russian Civil War|a multi-sided civil war]].

In July 1918, President Wilson asked the Japanese government to supply 7,000 troops as part of an international coalition of 25,000 troops planned to support the [[American Expeditionary Force Siberia]]. Prime Minister [[Terauchi Masatake]] agreed to send 12,000 troops but under the Japanese command rather than as part of an international coalition. The Japanese had several hidden motives for the venture, which included an intense hostility and fear of communism; a determination to recoup historical losses to Russia; and the desire to settle the ''"northern problem"'' in Japan's security, either through the creation of a buffer state or through outright territorial acquisition.

By November 1918, more than 70,000 [[Imperial Japanese Army|Japanese troops]] under Chief of Staff Yui Mitsue had occupied all ports and major towns in the [[Primorsky Krai|Russian Maritime Provinces]] and eastern [[Siberia]]. Japan received 765 [[Polish people|Polish]] orphans from Siberia.<ref>{{cite web |title=Question 1917年（大正6年）のロシア革命時に、シベリアに在留していたポーランド孤児を日本政府が救済したことについて調べています。 |publisher=[[Ministry of Foreign Affairs of Japan]] |url=http://www.mofa.go.jp/mofaj/annai/honsho/shiryo/qa/taisho_01.html#0908_02 |access-date=October 3, 2010}}</ref><ref>{{cite web |title=Polish orphans |publisher=[[Tsuruga, Fukui|Tsuruga city]] |url=http://www.city.tsuruga.lg.jp/sypher/free/kk-museum/polish-orhpans/polish-orhpans.html |access-date=October 3, 2010 |url-status=dead |archive-url=https://web.archive.org/web/20101112081121/http://www.city.tsuruga.lg.jp/sypher/free/kk-museum/polish-orhpans/polish-orhpans.html |archive-date=November 12, 2010}}</ref>

In June 1920, around 450 Japanese civilians and 350 Japanese soldiers, along with Russian White Army supporters, were massacred by partisan forces associated with the [[Red Army]] at [[Nikolayevsk Incident|Nikolayevsk on the Amur River]]; the United States and its allied coalition partners consequently withdrew from Vladivostok after the capture and execution of White Army leader Admiral [[Aleksandr Kolchak]] by the Red Army. However, the Japanese decided to stay, primarily due to fears of the spread of Communism so close to Japan and Japanese-controlled Korea and Manchuria. The Japanese army provided military support to the Japanese-backed [[Provisional Priamurye Government]] based in Vladivostok against the Moscow-backed [[Far Eastern Republic]].

The continued Japanese presence concerned the United States, which suspected that Japan had territorial designs on Siberia and the Russian Far East. Subjected to intense diplomatic pressure by the United States and United Kingdom, and facing increasing domestic opposition due to the economic and human cost, the administration of Prime Minister [[Katō Tomosaburō]] withdrew the Japanese forces in October 1922. Japanese casualties from the expedition were 5,000 dead from combat or illness, with the expedition costing over 900&nbsp;million yen.