Emigration Restrictions and Defectors
In 1917, Russia restricted emigration by instituting passport controls and forbidding the exit of belligerent nationals. In 1922, after the Treaty on the Creation of the USSR, both the Ukrainian SSR and the Russian SFSR issued general rules for travel that foreclosed virtually all departures, making legal emigration impossible. Border controls thereafter strengthened such that, by 1928, even illegal departure was effectively impossible. This later included internal passport controls, which when combined with individual city Propiska ("place of residence") permits, and internal freedom of movement restrictions often called the 101st kilometre, greatly restricted mobility within even small areas of the Soviet Union.
After the creation of the Eastern Bloc, emigration out of the newly occupied countries, except under limited circumstances, was effectively halted in the early 1950s, with the Soviet approach to controlling national movement emulated by most of the rest of the Eastern Bloc. However, in East Germany, taking advantage of the Inner German border between occupied zones, hundreds of thousands fled to West Germany, with figures totaling 197,000 in 1950, 165,000 in 1951, 182,000 in 1952 and 331,000 in 1953. One reason for the sharp 1953 increase was fear of potential further Sovietization with the increasingly paranoid actions of Joseph Stalin in late 1952 and early 1953. 226,000 had fled in the just the first six months of 1953.
With the closing of the Inner German border officially in 1952, the Berlin city sector borders remained considerably more accessible than the rest of the border because of their administration by all four occupying powers. Accordingly, it effectively comprised a "loophole" through which Eastern Bloc citizens could still move west. The 3.5 million East Germans that had left by 1961, called Republikflucht, totaled approximately 20% of the entire East German population. In August 1961, East Germany erected a barbed-wire barrier that would eventually be expanded through construction into the Berlin Wall, effectively closing the loophole.
With virtually non-existent conventional emigration, more than 75% of those emigrating from Eastern Bloc countries between 1950 and 1990 did so under bilateral agreements for "ethnic migration." About 10% were refugee migrants under the Geneva Convention of 1951. Most Soviets allowed to leave during this time period were ethnic Jews permitted to emigrate to Israel after a series of embarrassing defections in 1970 caused the Soviets to open very limited ethnic emigrations. The fall of the Iron Curtain was accompanied by a massive rise in European East-West migration. Famous Eastern Bloc defectors included Joseph Stalin's daughter Svetlana Alliluyeva, who denounced Stalin after her 1967 defection.
Read more about this topic: Eastern Bloc