Ka cika wannan jumla: A watan Agusta na shekara ta 1939, Nazi da Jamus da kuma Tarayyar Soviet sun rattaba hannu a kan yarjejeniyar Molotov-Ribbentrop, wadda ta ba da ƙasar Finland da kuma ƙasashen Baltic ga "yanayin rinjayar" na Soviet. Bayan mamayewar Poland, Tarayyar Soviet ta aika da umarni ga kasashen Baltic, inda ta bukaci sansanonin soji a ƙasarsu. Kasashen Baltic sun yarda da bukatun Soviet, kuma sun rasa 'yancin kansu a lokacin rani na 1940. A watan Oktoba na 1939, Tarayyar Soviet ta aika da irin wannan buƙata ga Finland, amma Finns sun ƙi ba da kowane yanki na ƙasa ko sansanonin soja don amfani da Red Army. Wannan ya sa Soviet Union ta fara wani
mamayewar soja a kan Finland a ranar 30 ga Nuwamba 1939. Shugabannin Soviet sun yi hasashen cewa za a ci Finland a cikin makonni biyu. Duk da haka, duk da cewa Red Army yana da babban rinjaye a cikin maza, tankuna, bindigogi da jiragen sama, Finns sun iya kare kasarsu na kimanin watanni 3.5 kuma har yanzu sun guje wa mamayewa cikin nasara. Yaƙin hunturu ya ƙare a ranar 13 ga Maris, 1940 tare da yarjejeniyar zaman lafiya ta Moscow, wanda Finland ta rasa Karelian Isthmus ga Tarayyar Soviet. Yakin hunturu ya kasance babbar asara ga Tarayyar Soviet, kuma an fitar da ita daga League of Nations saboda harin da ba bisa ka'ida ba. Finland ta sami kyakkyawar niyya ta duniya da taimakon kayan aiki daga ƙasashe da yawa a lokacin yaƙin.