Final answer:
The former allies of Russia during World War I got involved in the Russian Civil War to support the counterrevolutionaries against the Bolsheviks.
Step-by-step explanation:
The former allies of Russia during World War I, including the United States, got involved in the Russian Civil War to support the counterrevolutionaries known as the White Russians against the Bolsheviks. They sent thousands of troops to Siberia between 1918 and 1920 in an attempt to prevent the Bolsheviks from seizing control. The Allies, motivated by their opposition to the Bolshevik regime and the fear of its spread, aimed to protect their own interests and promote their vision for post-war Europe.