Operation Rubikon was a secret collaboration between the German BND and the American CIA.
They secretly bought the Swiss company Crypto AG, which sold encryption devices worldwide.
These devices were manipulated so that the secret services could read the actually encrypted messages from many countries.
The operation ran for decades (around 1970-1990s) and became public knowledge in 2020 through media research.
Posted by Schpitzchopf_Lorenz