The outbreak of World War II dramatically altered Soviet Ukraine's territorial boundaries through Stalin's aggressive expansionism. The Molotov-Ribbentrop Pact of August 1939, with its secret protocols dividing Eastern Europe between Nazi Germany and the Soviet Union, provided the framework for Soviet territorial acquisitions that would fundamentally reshape Ukraine's borders while intensifying Russification policies.
The Soviet invasion of Poland on September 17, 1939, following Germany's attack from the west, enabled Moscow to seize territories long coveted by Ukrainian nationalists. Eastern Galicia and Volhynia, regions with substantial Ukrainian majorities under Polish rule since 1921, were rapidly occupied by the Red Army. The Soviet regime presented this annexation as "liberation" of oppressed Ukrainians from Polish control, and in November 1939, these territories were formally incorporated into the Ukrainian SSR. However, this expansion brought not Ukrainian cultural renaissance but Soviet terror. The NKVD immediately began mass arrests, deportations, and executions targeting Polish officials, landowners, intellectuals, and Ukrainian nationalists alike. Russification intensified as Soviet institutions replaced Polish administration, with Russian becoming the language of power despite Ukrainian numerical dominance.
In June 1940, Stalin exploited European chaos to issue an ultimatum to Romania, demanding Bessarabia and Northern Bukovina. Romania, isolated and facing German pressure, capitulated without resistance. Soviet troops occupied these territories immediately, with Northern Bukovina and some Bessarabian territories incorporated into the Ukrainian SSR in August 1940. Again, Moscow portrayed this as rectifying historical injustice, but the reality involved brutal Sovietization. Mass deportations to Siberia and Kazakhstan targeted Romanian officials, intellectuals, clergy, and prosperous peasants. The Russification apparatus transplanted from eastern Ukraine imposed Soviet cultural conformity, suppressing both Romanian and Ukrainian cultural expression in favor of Russian linguistic and cultural dominance.
These territorial acquisitions significantly enlarged Soviet Ukraine, adding millions of inhabitants and economically important regions. However, they also imported populations with recent experience of non-Soviet rule, creating security concerns for Moscow. The resulting repression proved particularly severe, as Stalin's regime sought to break any potential resistance before it could organize.
The Crimean Autonomous Soviet Socialist Republic remained within the Russian SFSR throughout this period, despite Ukraine's territorial expansion. Moscow retained direct control over this strategic peninsula, denying Ukrainian jurisdiction even as surrounding territories joined the Ukrainian SSR. This administrative separation reflected Crimea's military importance and Stalin's distrust of Ukrainian nationalism.
By June 1941, when Nazi Germany invaded the Soviet Union, Ukraine had achieved its largest territorial extent under Soviet rule, yet Russification and totalitarian control had only intensified, crushing hopes that territorial expansion might strengthen genuine Ukrainian cultural and political autonomy.
