Iran Nukes Forbidden?

Iran Nukes Forbidden?

I'd love to see a fuller explanation of the reasons behind this ruling, which is on IRNA here. Ayatollah Kashani says:

Islam bans shedding blood of nations; on the same ground, production of nuclear bomb and even thinking on its production are forbidden from Islamic point of view.

This is one of those times when I want to know why he says so. What's the justification for a ruling that even thinking of producing nuclear weapons is haram? I have no doubt that would be a fascinating conversation, one I'd like to have.