[LemmingLord]

How about this:

Nukes are a complete hoax. The "bombing" of hiroshima and nagisaki were actually natural disasters the americans were able to predict. All testing footage is a hoax to keep the ussr from taking more than its share of territory after world war II. If this gets out it will certainly change the balance of power in the world.. Expect invasions of some kind and a new world war that won't result in a holocaust...

The PCs might be a mission impossible style group, but after their first few missions when they realize the secret, the secret has already been shared with terrorists... and worse, South Korea actually succeeds in creating a REAL bomb and threaten the US to unleash it unless they relent in certain world affairs...