Rubuta ci gaba don wannan sakin layi - Tarayyar Soviet ta mamaye Poland a watan Satumbar 1939 a karkashin Yarjejeniyar Molotov-Ribbentrop da Jamus; Tarayyar Soviet ta mamaye Finland
a watan Nuwambar 1939; a watan Yunin 1941, Jamus ta soke yarjejeniyar rashin kai hari kuma ta mamaye Tarayyar Soviet. Kodayake USSR tana da fitattun masana kimiyya da injiniyoyi, sun fara bincike kan abin da daga baya zai zama radar ("radiolokatsiya", lit. radiolocation) da zaran kowa, kuma ya sami ci gaba mai kyau tare da haɓaka magnetron na farko, ya shiga yaƙin ba tare da wani filin ba, cikakken tsarin radar mai iya aiki.