In 1939, Finland attacked the Soviet Union first. Finland provoked the Winter War by shelling Mainila, a village on the USSR side of the border.
A "documentary" repeats at least ten lies about the 1939-1940 Winter War and Finnish-Russian relations. Debunked by the newspaper Ilta-Sanomat.
Shelling of Mainila was a false flag operation where the USSR itself shelled the village in 1939. The USSR claimed that the fire originated from Finland and that the Red Army had losses in personnel. It gave the USSR a pretext to launch the war.