What do you mean by "credibility"? By the definition as I understand it, "believability"...I don't see how the current war situation would affect that. If the U

What do you mean by "credibility"? By the definition as I understand it, "believability"...I don't see how the current war situation would affect that. If the US had destroyed many cities already, why wouldn't the Japanese believe that they'd be willing to destroy more? If you mean something like, "why would the threat to wipe out a city have an impact?"...I mean, clearly it did, because it led very quickly to surrender.