In 1920, USSR lost a war with Finland and the USSR had to shamefully sign the Treaty of Tartu
A "documentary" repeats at least ten lies about the Winter War and Finnish-Russian relations.
The "Kindred Nations Wars" in 1918-1920 were conflicts on the territories of the Soviet Russian side of the border. Finnish soldiers fought either to assert Finnish control over the areas inhabited by related Finnic peoples or to help them to gain their independence. Soviet Union did not lose a war, it did not even recognise that it would have been in a war. The treaty of Tartu in 1920 confirmed the border between Finland and Soviet Russia, and it followed the old border between the autonomous Grand Duchy of Finland and Imperial Russia. In the north, Finland additionally received Petsamo that, in 1864, tsar Alexander II had promised to join to Finland in exchange for a piece of the Karelian Isthmus.
Debunked by the newspaper Ilta-Sanomat