This is not entirely true. You had to apply to leave USSR and 90% were refused for one reason or another. Borders did not truly open until the 90s. Another unof

This is not entirely true. You had to apply to leave USSR and 90% were refused for one reason or another. Borders did not truly open until the 90s. Another unofficial motivation was in lines with "equity". Universities were trying to meet USSR's unofficial quotes per nationality. I heard China was/is trying to do something similar