A watan Nuwamba na shekara ta 1939, Soviet Union ta kai wa ƙasar Finland farmaki
, wanda ya haifar da mummunan hasara da kuma shigar da yarjejeniyar zaman lafiya na wucin gadi a watan Maris na 1940 wanda ya baiwa Tarayyar Soviet yankin gabashin Karelia (10% na yankin Finnish). A tsakiyar watan Yunin 1940, yayin da aka mai da hankali ga kasashen duniya kan mamayewar Jamus a Faransa, sojojin Soviet NKVD sun mamaye wuraren da ke kan iyaka a Lithuania, Estonia da Latvia kuma sun maye gurbin kowace gwamnati da 'yan siyasa masu goyon bayan Soviet, wadanda suka nemi shigar da kasashensu zuwa Tarayyar Soviet. A watan Yuni, Soviets sun ba da umarnin da ke buƙatar Bessarabia, Bukovina, da kuma yankin Hertza daga Romania. Bayan Soviets sun yarda da Jamus cewa za su iyakance da'awar su a Bukovina zuwa arewacin Bukovina, Jamus ta bukaci Romania ta yarda da karshe. Kwana biyu bayan shigar Soviet, Romania ta amince da bukatun Soviet, kuma Tarayyar Soviet ta mamaye yankin.