I say if Iran wants to have nukes, let them.
Who's going to stop them, really? Us? Israel? And how, exactly, is that going to happen? Do you really think they care about economic sanctions and international condemnation if they're already working on nuclear weapons, especially if they're as far into it as the media machine would have us believe? Let's put it another way: suppose I have a nuclear device in my garage, and I have the capability of making more. Who's going to be brave enough to come and take it away from me? Do you think I'll be swayed by hollow words? "Stop! Or... I'll say stop again!"
It's not like Iran is going to massively destabilize or antagonize the Middle East or anything. We're doing a fine enough job of that ourselves.
When I was growing up, the Soviet Union was the enemy, Communism was evil, and we were supposedly at the nuclear brink throughout the 80s. Ronald Reagan spent us into oblivion, bankrupted the Soviets, and caused their nation to fall. Russia remained, as did several former Soviet republics, as independent sovereign nations (once known as breakaway republics). Some of these became "-stans" and are now Islamic states.
Now if I were, let's say, the Soviet Union in the 1980s, I don't think I'd hide all my nukes inside the Kremlin. I'd spread them around — some in the middle, some along the edges of the country, some up in the mountains, some out in the snows of Siberia, all over the place. Those Americans are crazy, you never know what they might try, so you've got to be ready for anything.
Continuing on... let's say I'm Turkmenistan or Uzbekistan near the end of the Soviet Empire. I've got a large Muslim population, and I know there's going to be a push for independence as soon as things start looking shitty. My allegiance is going to be for my own people, not for mother Russia. Now, let's imagine some of those aforementioned nukes reside within the boundaries of what will soon become my country. Maybe we'll keep a few just in case. Two? Three? Yeah, they won't miss two or three. Hell, they've got thousands of them (around 13,000), and everyone knows inventories always get screwed up anyway, right?
Let's say there weren't just two of those breakaway republics, but fourteen of them. Let's say they each kept two or three nuclear devices — again, just in case — and never told anyone. Did bankrupt, post-Soviet Russia have the resources necessary to account for all of them — especially right after the collapse? Want to take bets?
To add yet another variable into the mix, let's say they've got four nukes each. They could each sell two on the black market and keep two for themselves. Now everybody's got a shiny new toy to play with.
I think the genie has been out of the bottle for a long time, and they're all over the place. Trying to stop Iran from developing nuclear weapons is a fool's errand — I suspect they have no end of suppliers if that's what they want to do. And you know, if Iran is telling the truth and is just developing nuclear power instead, any attempts we make to block that progress will simply agitate and antagonize. And like I said before, we're already doing plenty of that.