Finland was granted independence by bolsheviks in 1917, and Finnish reactionaries immediately proceeded to drown their revolution in blood. After doing this they joined the white army general Yudenich preparing attack on Petersburg, but ultimately backed off since Yudenich superior, Kolchak, didn't even wanted to hear about independent Finland. But guess who supported that anyway? Mannerheim.

Finland was in every antisoviet bed possible since 1918.