How the KGB knew if you had a counterfeit passport or not
Secret agents and spys working for the U.S. are highly trained and funded. Despite that though, a simple problem exposed hundreds of them during the cold war, and it was not until the end of that “war” did we find out how the Soviet KGB were able to find out so fast if someone was a agent or not.
If you have ever shot old Russian ammo, chances are you shot corrosive rounds. Which means you have to clean your gun within a certain time frame after shooting or the barrel will start to rust. Ammo was not the only thing that was corroded though. Staples were too, and that is how the intelligence agency found spys easily. Something about the Soviet times and corroded goods.
In order to get into the USSR a agent would need a passport. Here is where the US made a big mistake. In the US, passport staples are made out of top quality stainless steel, in Soviet Russia, the staples were made out of cheap metal that corroded very fast. So when a agent tried to get into the Soviet Union, a KGB agent would look at their passport and if they saw that the staple looks brand new, chances are that the passport was fake. This is one of the many things the we learned after the USSR fell in 1991. Lucy Komisar of the Chicago Tribune wrote a great article about her visit to a KGB museum and all the things she saw. You can read that here.