Following the Russian October Revolution of November 1917, the new Bolshevik government in Russia signed a separate peace treaty with the Central Powers in March 1918.

In July 1918, against the advice of the United States Department of War, President Wilson agreed to send 5,000 US troops as the American North Russia Expeditionary Force (a.k.a.

Wilson appealed to Japan for a joint intervention to help the Czechs and suggested that they send no more than 7,000 men to Siberia, although Tokyo eventually sent ten times as many troops as this.

[13] The Canadian Siberian Expeditionary Force, authorised in August 1918 and commanded by Major General James H. Elmsley, was sent to Vladivostok to bolster the Allied presence there.

[17] The "Corpo di Spedizione Italiano in Estremo Oriente" was made of Alpini troops, supported by 2,500 Italian ex-POWs who had fought in the Austro-Hungarian Army and enrolled in the Legione Redenta.

The Italians played a small but important role during the intervention, fighting together with the Czechoslovak Legion and other allied forces using heavily armed and armoured trains to control large sections of the Siberian railway.

[20] However, the army general staff later came to view the Tsarist collapse as an opportunity to free Japan from any future threat from Russia by detaching Siberia and forming an independent buffer state.

After heated debate in the Diet, the administration of Prime Minister Terauchi Masatake agreed to send 12,000 troops, but under solely Japanese command, independent of the international coalition.

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.

[23] The American Expeditionary Force, Siberia was commanded by Major General William S. Graves and eventually totalled 8,763 officers and enlisted men.

[27] Unlike his Allied counterparts, General Graves considered his mission in Siberia to be to provide protection for American-supplied property and to help the Czechoslovak Legions evacuate Russia, and that it did not include fighting against the Bolsheviks.

Repeatedly calling for restraint, Graves was often at odds with commanders of British, French and Japanese forces who wanted the Americans to take a more active part in the military intervention in Siberia.

The French keep a very close eye on the British, and the Russians as a whole appear to be indifferent of their country's needs, so long as they can keep their women, have their vodka, and play cards all night until daylight.

Although many had linked up with the forces at Chelyabinsk by early July 1918, the area surrounding Lake Baikal was an obstacle that needed to be overcome before the Legion could get to Vladivostok.

In the area between the towns of Baikal and Kultuk on the southern point of the lake the Trans-Siberian railway ran through various tunnels, the final one of which was blown up by the Bolsheviks.

[34] It was decided that the American forces would not in any way fight the Bolsheviks and would simply stay behind and guard the section of the Trans-Siberian railway south of Khabarovsk and protect the military stores in Vladivostok.

[37] The force went forward with the advancing Czechs and Russians and continued to provide artillery support along the railway from Omsk to Ufa in October and November.

[40] Between May–July,[30] the British unit bombarded Red troop concentrations, protected bridges and provided direct fire support and attacked Bolshevik boats on the river.

[29] On 7 February 1920, White leader Admiral Kolchak was executed,[47] and in the next few months the Americans and the remaining Allied coalition partners withdrew from Vladivostok.

The Japanese army provided military support to the Japanese-backed Provisional Priamur Government based in Vladivostok against the Moscow-backed Far Eastern Republic.

Ostensibly, Japan, as with the United States and the other international coalition forces, was in Siberia to safeguard stockpiled military supplies and to "rescue" the Czechoslovak Legion.

However, the Japanese government's intense hostility to communism, a determination to recoup its past losses to Russia, and the perceived opportunity to settle the "northern problem" in Japan's security by either creating a buffer state,[20] or by outright territorial acquisition, were also factors.

However, patronage of various White movement leaders left Japan in a poor diplomatic position vis-à-vis the government of the Soviet Union, after the Red Army eventually emerged victorious from the Russian Civil War.