So during the end of WW1 and immediately after a number of nations sent what amounted to Peace Keepers to Russia to try and both keep a lid on the Russian Revolution and get the nation to stay in the fight against Germany.

Neither goal was a success as Russia devolved into Civil War, and signed a separate peace with the Central Powers and stayed out of the war till it ended. This additionally created problems for forces like the 10's of thousands strong Czech Legion which was essentially stranded in a failing state. Eventually they decided to take matters into their own hands and evacuate Russia by force along the Trans-Siberian Railway. Thus a multi national force of US, Canadian, French, British, and Japanese detachments occupied portions of the Russian Far East and while doing rather little fighting tried to allow for the evacuation of those who could or wanted to leave. A larger force of the same nations was also deployed in European Russia from Murmansk which took a more active role in fighting the Reds during the Civil War but it too was eventually withdrawn. In general and supported by many voices including Churchill's, the interventions were seen not just as a way to get an ally back fighting, but a chance to stop the cancer of Bolshevism in its crib before it could spread and export the Revolution.

You may be interested in this rather fine examination of the Allied interventions in Russia from the Canadian Force Journal by one Commander Moffat.