Adi Shamir (the S in RSA) was not allowed by NSA to attend a conference where he was going to present a paper about Nash’s asymmetric key algorithm.
I don’t attribute to malice that which can be explained by bureaucracy.
But this one seems suspicious. I would like to know what was inside Adi’s paper. Perhaps it had something about crypt analysis for RSA. And the NSA having known this beforehand didn’t want people to know.
Or perhaps, the NSA has something for American cryptographers eyes only.