You could find a little example of Soviet Union directly now in North Korea.
As you can see, it is totalitarian government that exactly a micro-copy of Soviet Union.
Why does traveling denied for North Korea's citizen? Because there is War. Great Cold War with 80+ years of history.
The same picture was in Soviet Union.
Evil capitalist with CIA ( Central Intelligence Agency of USA ) dreamt to stop Red plague anyhow. Their methods was similar to todays. It is bribery. You can read about Economic Hit Mans. And thereafter - real assassinations with massacre and False flag's actions.
In such World, only soldiers of this War could travel abroad, its were spies of KGB and this travellings was Battles, for a long time. Other people were tracked by this army of spies for their safety and for the safety of Soviet System.
KGB knew about "Mind control" researches of CIA. Of-course, they knew about dirty games of Hitler's special services ( SS ). About German's Ahnenerbe.
However, "Soviet mind control research consistently lagged years behind American efforts". You could read about CIA's Project BLUEBIRD. About Artichoke project, about Castigate ( 1952 ), MKNAOMI ( 1952 ) and of-course about MKULTRA.
As you can get, the real CIA's aim was a MIND.
This, may be, I'm not sure, was one of the reasons to safe Soviet citizen from the capitalist's countries. Anyway, Soviet country was located over 1/6 part of the The Earth's lands. Soviets were counting that peoples on the American continent were more conscious. That they will trying to dismiss Capitalists government. This lands ( USA, Western Europe, ... ) was a battlefield for Global Planetary Communism. So, can you let civilian to travel over the battlefield without cover? No. They will be killed directly in their MIND by CIA's special squads MKULTRA-based.