Stephen Walt claims that Iran going nuclear won’t change much:
[B]oth theory and history teach us that getting a nuclear weapon has less impact on a country’s power and influence than many believe, and the slow spread of nuclear weapons has only modest effects on global and regional politics. Nuclear weapons are good for deterring direct attacks on one’s homeland, and they induce greater caution in the minds of national leaders of all kinds. What they don’t do is turn weak states into great powers, they are useless as tools of blackmail, and they cost a lot of money. They also lead other states to worry more about one’s intentions and to band together for self-protection. For these reasons, most potential nuclear states have concluded that getting the bomb isn’t worth it.
But a few states-and usually those who are worried about being attacked-decide to go ahead. The good news is that when they do, it has remarkably little impact on world affairs.
Including Mao’s China – even in its most insane, totalitarian period. Containment of Iran is as possible for us now as containment of the USSR was for decades. It’s staggering to me that this position – once mainstream – is now unrepresented in both major political parties.