A Hungarian professor of mine, who grew up under socialism during the 60s and 70s, said that in his experience, it wasn’t very hard to get to the “west.” The government didn’t really care if you emigrated or not; but they did want to reduce tourism, since the monetary systems of east and west weren’t compatible. Significantly, he said, the western countries themselves weren’t particularly keen on tourists from the COMECON bloc, since there was a fear that cheap goods from socialist countries would make their way into the black market and cause destabilization. That is, you could buy (say), ten cases of baby formula in Hungary, and sell them in West Germany for a fraction of their market value; and because of price controls in the east, you would still make a big profit. Thus, customs were very strict when you were going over the border.

The biggest fear of the US has been that socialist nations (1) surpass capitalism economically, and (2) engage in massive global trade. With China, that fear has basically been realized.