Answer
In 1980, Korchnoi became a Swiss citizen. He had been living in Switzerland since 1976, and he had been married to a Swiss woman since 1975. Korchnoi had been a Soviet citizen since 1956, but he had become increasingly critical of the Soviet government in the 1970s. In 1976, he had been stripped of his Soviet citizenship, and he had been banned from competing in the Soviet Union.