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.

Expeditionary warfare is a military invasion of a foreign territory, especially away from established bases. Expeditionary forces were in part the antecedent of the modern concept of rapid deployment forces. Traditionally, expeditionary forces were essentially self-sustaining with an organic logistics capability and with a full array of supporting arms.