The impact of foreign countries on the Civil War was minimal for a number of reasons:
By the end of 1919 most foreign troops had left Russia. But the Reds used the idea of foreign support for the White armies as propaganda. They claimed that the White generals were attempting to defeat the Bolsheviks in order to hand Russia over to foreign imperialists.
The fear of losing their independence convinced a great deal of Russians to support the Reds. As a result, the Reds established themselves as the saviours of Russia.