[quote=@Isotope]
Could we just say that its a legend across the world?  I'd rather there not be massive and widespread knowledge of a giant armed satellite formation.

On that note, just have it target centrifuges and anything like them  Say it can see through the ground.
[/quote]Can you be a bit more coherent here?
I really don't understand you. For starters the 50s is pretty much the beginning of information age. Humble beginnings but still a stage where you no longer keep such things under the radar. Second what good is in targeting centrifuges?
The point is that some foreign mechanism is in space which delivers a return strike at any nation which succeeds delivering a nuke. It's intended to be a well understood fact how and why this system activates and the undeniable proof for historians that the world was once nearly destroyed and now history had almost repeated itself.
What's the problem with that?