Not only to the bloc countries, but even travel entirely within Russia was also restricted and bureaucratically regulated, requiring internal passports and visa

Not only to the bloc countries, but even travel entirely within Russia was also restricted and bureaucratically regulated, requiring internal passports and visas for travel. https://en.wikipedia.org/wiki/Passport_system_in_the_Soviet_Union#1932%E2%80%931991 https://en.wikipedia.org/wiki/Passport_system_in_the_Soviet_...