Hasan Sarbakhshian, Associated Press
Iranian President Mahmoud Ahmadinejad speaks during a ceremony at Iran's nuclear enrichment facility in Natanz, Iran, last year.

Hillary Clinton promises she'd "obliterate" Iran if it used nuclear weapons against Israel, suggesting that, as president, she'd return the "favor" — in spades.

Putting aside campaign rhetoric, the senator raises an excellent point: What will America do when Iran gets nuclear weapons? Many national security experts still think Washington can stop Tehran's reach for the bomb. I am not one of them. Iran has already achieved a sloppy, asymmetrical form of nuclear deterrence, meaning we can't stop it from "getting nuclear" unless we "go nuclear" pre-emptively, something we won't do.

America could stop Iran with a massive conventional invasion, but that's not something we can pull off in time.

We also can't eliminate Iran's program through conventional bombing. We can certainly raise a lot of sand, but Iran's been smart enough to distribute its assets and bury them deep underground, learning from Israel's strikes against Iraq decades ago.

Yes, Israel might strike pre-emptively with nukes. That remains the big wild card.

But let's be clear that Israel would be protecting its long-standing regional monopoly on weapons of mass destruction. That monopoly hasn't kept Israel safe from conventional military attack; Israel's military superiority does that. It also hasn't prevented terrorism, even though Israel maintains a world-class defensive capacity there too.

All Tel Aviv's WMD monopoly generates is diplomatic opportunity: As soon as somebody else in the region gets a few nukes to challenge Israel's roughly 200 warheads, the world's great powers will collectively force direct negotiations leading to — at least — a bilateral strategic arms treaty between the two states.

Why? We'll all find the resulting situation too much to bear, not just in the West but far more in the East, which relies on Persian Gulf energy too much to suffer such strategic uncertainty.

What does that get us? It gets us Iran having to recognize Israel to achieve its primary goal in pursuing a nuclear capacity — namely, America's promise not to engage in forcible regime change in Tehran.

Since that goal will be effectively achieved by Tehran's looming nuclear capacity anyway, then we're heading into a different dynamic: Simultaneously creating a stable nuclear stand-off between Israel and Iran, a dyad that quickly becomes a triad if Saudi Arabia decides that Arab Sunnis need their own nuclear champion to balance the Persian Shiites.

For many regional and nuclear experts, such developments would constitute an almost unthinkably unstable strategic situation, but again, the only way to stabilize such a situation would be to force a trilateral or even regional security scheme that acknowledges each state's nuclear weapons explicitly and links those capabilities to one another through the condition of mutually-assured destruction.

Pursued intelligently by outside great powers, Iran's reach for the bomb could end up being the event that makes real peace in the Middle East truly possible. No, I don't expect any outside great powers, especially the United States, to acquiesce to Iran's nuclear efforts. I expect them to try and stop that outcome from unfolding, but once those efforts prove insufficient, then we'll collectively shift to the dynamics I've just described.

When that moment comes, one thing will have to be made crystal clear to Tehran: If Iran attacks Israel with nuclear weapons, the United States would retaliate massively with nuclear weapons, effectively ending Iran's existence as a nation. Absent that firm guarantee, we'd put Israel into the scary situation of worrying about its second-strike capability.

And yes, America would need to make the same position clear to a nuclear-capable House of Saud.

Too scary to contemplate? Hardly.

We've covered this territory before and ended a great power war across the Eurasian landmass in the process. Now, we're simply facing similar possibilities — and dangers — in the Middle East.

In this journey, offering the right promises to wage unlimited war will get us the best opportunities to forge a permanent peace.

Thomas P.M. Barnett ([email protected]) is a visiting scholar at the University of Tennessee's Howard Baker Center and the senior managing director of Enterra Solutions LLC.