Could We Tolerate Nuclear-Armed Iran?

As the ceasefire between Israel and Iran seems to be holding for now, it is important to reflect on whether this whole episode was worth the risks.

Wider escalation was (and remains) possible, and we do not know whether Iran will seek a nuclear weapon with renewed vigour in the future.

So, could we live with a nuclear-armed Iran, if it does indeed continue to pursue a bomb?

Is an Iranian bomb an existential threat?

The conventional wisdom, at least in the Western world, is that an Iranian nuclear weapon would pose an existential threat to Israel, and possibly the United States as well.

Israeli Prime Minister Benjamin Netanyahu said his country's strikes on Iran's nuclear facilities were aimed at rolling back "the Iranian threat to Israel's very survival".

White House press secretary Karoline Leavitt described an Iranian bomb as "an existential threat, not just to Israel, but to the United States, and to the entire world".

The same mantra has been repeated by leaders in Europe , at the G7 meeting , and in Australia .

Iran, of course, did not yet possess a nuclear weapon when the strikes occurred, as the UN nuclear watchdog attested . The strikes were aimed at preventing Iran from being able to do so in the future - a prospect seen by Israel and the US as simply " unthinkable ".

But if Iran had built a nuclear weapon before the Israeli and US strikes - or manages to do so in the future - would this pose an existential threat to Israel or the US?

The answer is no. And for a very simple reason: nuclear deterrence works .

Why deterrence works

If Iran had a monopoly on nuclear weapons, it would be different. But it does not.

Israel has maintained a robust nuclear arsenal for more than half a century . Every authoritative assessment of global nuclear weapons stockpiles includes Israel's roughly 90 nuclear warheads .

The Israeli government officially neither confirms nor denies the existence of its nuclear arsenal. But thanks to leaks from inside the Israeli nuclear program - as well as the best assessments from around the world - we can be quite sure they exist. It also explains why Israel has never signed the Nuclear Non-proliferation Treaty - it can't without giving up this stockpile.

The US, of course, has been nuclear-armed since 1945 and openly maintains an inventory of thousands of nuclear warheads. These provide a deterrent against nuclear attacks on the United States.

Washington also provides extended nuclear deterrence guarantees to over 30 states, including members of NATO, Japan, South Korea and Australia. It does not need to provide this for Israel given the Israeli arsenal. But if there was ever any doubt about Israel's stockpile, it certainly could.

After 80 years of living with nuclear weapons, we know the deterrent effect of assured nuclear retaliation is very powerful. It deterred both the Soviets and Americans from using nuclear weapons against each other through multiple Cold War crises. It has deterred both India and Pakistan from using them in multiple standoffs, including quite recently . It has deterred both North Korea and the US from striking each other.

Similarly, Iran would no doubt be deterred from using a nuclear weapon by a certain Israeli or American response.

Iranian leaders have called for the destruction of Israel, and the chants of "death to Israel" and "death to America" are a common occurrence at rallies held by supporters of the regime.

But beneath the fiery rhetoric lies a truism: no Iranian leader would destroy Israel with a nuclear weapon if it came at the expense of the destruction of Iran.

In the history of the nation-state, not a single one has ever knowingly committed suicide. Not for any reason - ideological, religious, political or any other. All nations value survival over everything else because this allows for the achievement of other goals, such as power and prosperity.

Further, Iran is ruled by a brutally authoritarian, theocratic regime. And for authoritarian regimes, staying in power is the number one priority. There is no staying in power the day after a nuclear exchange.

Not a panacea

This does not mean an Iranian nuclear weapon would be a welcome development. Far from it.

Every new nuclear-armed state provides another opportunity for miscalculation or accident. It adds extra stress to an already fragile non-proliferation regime .

In addition, nuclear deterrence is not just and can be considered ethically questionable . It may not even be sustainable over the longer term .

There is no doubt the existence of over 12,000 nuclear weapons globally poses a potentially existential risk to all of humanity.

But the idea that a nuclear-armed Iran would pose a unique risk to Israel or the United States simply does not stand up to scrutiny. If we can live with a nuclear-armed North Korea, nuclear-armed Pakistan, and for that matter, a nuclear-armed Israel, we can live, however reluctantly, with a nuclear-armed Iran.

Regardless of whether the current proposed ceasefire between Israel and Iran holds, the military operation initiated by Israel and bolstered by the United States was extremely dangerous and unnecessary, based on both countries' justification.

The regime in Tehran is brutal , authoritarian, openly antisemitic and worthy of our disdain. But there is no evidence it is suicidal.

The claim an Iranian nuclear bomb would pose an existential threat to Israel or the United States and justifies unilateral, preventive military attacks makes no sense.

It is time to stop repeating it.

Benjamin Zala has received funding from the Stanton Foundation, a US philanthropic group that funds nuclear research. He is an honorary fellow at the University of Leicester on a project that is funded by the European Research Council.