"Why, exactly, would a nuclear Iran be so much worse than a non-nuclear Iran?"

"... Why, exactly, would a nuclear Iran be so much worse than a non-nuclear Iran? Bear with me here: Let's say Iran gets a nuclear weapon. What happens next? Would other states bandwagon? What would that bandwagoning behavior look like in real terms? (For the record, I have never heard any compelling answer to this question in travels around the region.)

Would other states seek nuclear weapons? How, exactly? Let's pick one example: Saudi Arabia. Why, first off, has Saudi Arabia not already begun a nuclear energy program? (And don't say "oil," because there is an opportunity cost to Gulf states using oil for their own energy rather than selling it on the open market for $100 a barrel.) Does Saudi Arabia have the technical expertise to start a nuclear program? If so, how long would it take them? Would Saudi Arabia instead buy a bomb? From where? From Pakistan, perhaps? Why would the Pakistanis sell one to them? Why might the Pakistanis not sell one to them? You can see where I am going here: once you start trying examine the second and third order effects and their various branches, it's tough to explain how, exactly, a nuclear Iran would be that much more dangerous than a non-nuclear Iran. I am not saying it would not be more dangerous -- I am saying it is very hard to explain how, exactly, a nuclear Iran would be more dangerous. And I think those arguing for war with Iran have an obligation to sketch out those specifics to both policy makers and to the public.

On the flip side of the equation, what might be the adverse second and third order effects of a U.S. strike on Iran? I agree with Matt's critics that he gives us the best-case scenario. But how does the situation look if we work through the effects of a U.S. strike on Iran country-by-country? How might another war affect U.S. security and economic interests elsewhere in the region? How might such a war affect U.S. interests outside the region? How might Iran respond?

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