I'm just curious on how the Hidden Nuke Silo functions.

I understand it protects 5 nukes from being spied, but does it only work on 20+ nukes or will it always protect 5 nukes even if you had 1 left?

Thanks.

It will always protect the last five that you have. So it will protect nukes 1-5, whilst 6-25 are still vulnerable.

As Aimee Mann said, you can purchase 5 extra nukes up to a maximum of 25. You won't notice the effect (other than the extra maximum stockpile) until you have 5 or fewer nukes remaining at which point they are all protected from spy attacks.

Answered and locked.