The Allied intervention in the Russian Civil War consisted of a series of multi-national military expeditions that began in 1918. The initial impetus behind the interventions was to secure munitions and supply depots from falling into the German Empire's hands, particularly after the Bolsheviks signed the Treaty of Brest-Litovsk, and to rescue the Allied forces that had become trapped within Russia after the 1917 October Revolution. After the Armistice of 11 November 1918, the Allied plan changed to helping the White forces in the Russian Civil War. After the Whites collapsed, the Allies withdrew their forces from Russia by 1925.

The Siberian intervention or Siberian expedition of 1918–1922 was the dispatch of troops of the Entente powers to the Russian Maritime Provinces as part of a larger effort by the western powers, Japan, and China to support White Russian forces and the Czechoslovak Legion against Soviet Russia and its allies during the Russian Civil War. The Imperial Japanese Army continued to occupy Siberia even after other Allied forces withdrew in 1920.