The Shelling of Mainila (Finnish: Mainilan laukaukset, Swedish: Skotten i Mainila, Russian: Ма́йнильский инциде́нт, romanized: Máynil'skiy intsidént) was a military incident on 26 November 1939 in which the Soviet Union's Red Army shelled the Soviet village of Mainila (Russian: Ма́йнило, romanized: Máynilo) near Beloostrov. The Soviet Union declared that the fire originated from Finland across the nearby border and claimed to have had losses in personnel. Through that false flag operation, the Soviet Union gained a great propaganda boost and a casus belli for launching the Winter War four days later.Historians have now concluded that the shelling of Mainila was a fabrication carried out by the Soviet NKVD state security agency.