A New-clear Deal with Iran

A brief primer on the current situation

Russia is in Ukraine, the US is attempting a pivot to Asia and is in the midst of negotiations with Iran over its nuclear program. No, you didn’t wake up in 2015. It’s 2025 and the last 10 years actually happened.

Iran kicked up its uranium enrichment in November 2024, coinciding with Trump’s election. In November Iran had a stockpile of 182 kg of 60% enriched uranium. As of February, that had gone up to 275 kg, which is roughly enough for a half-dozen bombs. This increase in enrichment activity has prompted threats of military action from the Trump administration, although it has also started a renewed push for a deal. Trump reportedly turned down an Israeli proposal for a joint strike on Iranian nuclear facilities, so diplomacy may have its day. Indeed, Washington and Tehran have held several talks with both sides being cautiously optimistic on their outcome. So will there be (another) Iranian nuclear deal?

First, let’s define enriched uranium so we can sound smart at dinner parties.

What’s enriched Uranium?

There are 3 naturally occurring uranium (U) isotopes: U-238, U-235, and U-234.¹ U-238 is the most abundant at about 99.3% of all uranium by mass, followed by U-235 at 0.7%, with U-234 being a rounding error. So uranium ore will primarily contain U-238 with a bit of U-235 in it. U-238 isn’t fissile, meaning it can’t be used for nuclear fission. But 235 is fissile.

Because of the difference in the number of neutrons in each isotope’s nuclei, they have slightly different masses (atomic mass of 238 vs 235). By spinning uranium hexafluoride gas very fast in specialized centrifuges, you can gradually separate out more and more of U-238 leaving more of U-235.² This is the process of enrichment. Once you get the percentage of U-235 up to 3.67%, you can put it into nuclear reactor and produce power. At 20% you have highly-enriched uranium (HEU), which is weapons-usable for rudimentary bombs. At around 90% you have weapons-grade uranium.

Now let’s get back to Iran.

How long until Iran gets the bomb?

Iran has two known enrichment sites; Natanz and Fordow. The former is out in the open, albeit with a thick concrete shield while the latter is built deep underground in a mountain for protection from airstrikes. This is prudent because Israel has a habit of striking nuclear sites of Middle Eastern rivals.³

As mentioned before, Iran is sitting on at least 275 kg of 60% enriched uranium. That’s far from 90%, right? Wrong. As the concentration of U-235 increases, it gets easier to separate out the U-238. So 60% is actually close to 90%. Estimates on how long it would take Iran to produce enough 90% enriched uranium for a nuclear bomb range from months to weeks, but is probably on the shorter side.

But months to weeks isn’t how long it would take to build a device. There is still the process of weaponization. They would need to develop the trigger mechanism; either a gun-type or an implosion-type trigger. Implosion triggers are comparatively complicated and would need extensive testing; although they’d need to test the gun-type as well. Then they’d need to build a warhead that can fit on a missile, unless they wanted to deliver it on a truck or something. Next, they’d need a missile capable of delivering the warhead. Unfortunately, they probably have multiple ballistic missile types that are capable of delivering a nuclear payload. For example the Ghadr and the Shahab-3 (which is based on North Korea’s Nodong). Either of which has enough range to strike pretty much anywhere in the Middle East, depending on the payload size.

The US intelligence community concluded that Iran wasn’t undergoing weaponization research until recently. Estimates on how long it would take to build the capability to deliver a nuclear payload range from several months to a year. Since they could enrich their uranium to weapons-grade concurrently with weaponization research, that is the length of time it would take them to race to a bomb.⁴

Why does Iran want nukes?

Let’s take a step back and ask, “Why does Iran want the bomb?”⁵ Iran is a regional power and it wants to be THE regional power. That said, I’m not sure it wants the bomb. I think it wants the threat of building the bomb. Matthew Fuhrmann in his new book outlines how the threat of building a nuke gives Iran leverage.⁶ He outlines three reasons why the threat of building the bomb is useful:

1. Deterrence by Proliferation

   1. The ability to threaten to possess nukes gives bargaining power to the extent other countries don’t want the threatening party to have it.

2. Delayed Retaliatory Strikes

   1. Basically traditional deterrence with a delay in retaliatory strikes.

3. Deterrence by Doubt

   1. If a state may already have the bomb, other states may treat it like it already does (see Israel).

Basically, influence and leverage.

Ignoring nukes, how’s Iran’s pursuit of regional hegemony going?

Iran and its Axis of Resistance have had a rough go of it lately.

• Hamas’ capabilities are greatly diminished from its war with Israel.

• Hezbollah’s got a bad batch of pagers, lost its leader, and lost its parliamentary majority in Lebanon in 2022. It is still a force, but it is somewhat diminished.

• Assad’s government fell in Syria, which additionally cuts off the land route for Iran to supply Hezbollah.

I think the Shiite militias in Iraq are doing alright. The Houthis were successful in causing pain to Israel and the Western world by shooting at ships going through the Bab el-Mandeb, although they’ve reached a ceasefire with the US in response to its bombing campaign.⁷ On balance, Iran’s regional position is weaker than it was several years ago.

Let’s make a deal!

I think there is plenty of room to make a deal and plenty of incentives against escalation on both sides. Iran’s economy has been battered by sanctions for decades. Sanctions relief is a strong pull for them to make a deal, as it was in 2015. The US doesn’t want another war in the Middle East. Wars, even limited ones, are costly and the US wants to pivot to Asia (also nuclear proliferation bad).

Escalation would be bad for all parties. Here are some (non-extensive) possibilities of what escalation could look like:

Step 0:

• Everyone accepts the status quo (Stop here)

• Everyone doesn’t (move to Step 1)

Step 1:

• US/Israel makes the first move.

  • The US or Israel strike Iranian nuclear program targets like Natanz and Fordow.

• Iran makes the first move.

  • Iran races for the bomb and the US/Israel strike nuclear program targets like Natanz and Fordow.

Step 2:

• Iran can:

  • make a purely face saving strike and everyone goes on with their day. (Stop here)

  • Escalate

    • Persuade the Houthis to break the ceasefire agreement with the US and resume harassing all Western vessels trying to navigate the Bab el-Mandeb

    • Launch missiles at US bases in the region/Israel

    • Ramp up nuclear activities at unknown sites (if they exist)

    • Restrict oil flow through the Hormuz Strait causing chaos in oil markets⁸

      • Can be through grey methods like boarding and harassing tankers

      • Laying mines in the strait

      • Using military force (missiles or naval) on tankers

Pretty bad, huh? From here it escalates more until there is capitulation or war. But you can see how there are no winners in escalation. The potential costs are very high if there is no deal or acceptance of the status quo. That means there is a lot of room for a deal. Now for the forces working against a deal.

James Fearon lays out 3 sources of war in his bargaining model:

• Indivisibility of a good

  • This may apply here. I’m not sure Iran actually wants the bomb or just the ability to build it, although I strongly lean toward the latter.

    • If the really want the bomb, we have a problem.

    • If it’s the latter, there is probably room for monitors to monitor their activity.

      • If the US and Israel are alright with Iran having the technical capability of building a bomb, Iran gets influence, while everyone else gets the ability to know if they’re trying to breakout.

        • Not optimal, but it’s better than not knowing.

      • If Iran feels it needs the ability to enrich uranium while everyone else disagrees, we have an indivisible good.

• Uncertainty

  • Iran doesn’t know the US’s actual red lines and vice versa.

    • The US said they can enrich up to 3.67% and then reversed its statement saying any enrichment is a red line.⁹

      • Possibly just jockeying for negotiating leverage.

  • The US/Israel might not know all of Iran’s nuclear current capabilities.

  • Israel is a wildcard.

• Commitment problems

  • Trump does have a history of withdrawing from nuclear deals with Iran.

I think there are some significant obstacles in the way of another US-Iran nuclear deal. But the costs are so high I think the range of acceptable bargains make a deal more likely than not. At the time of writing this, Polymarket has the probability of an deal in 2025 at 71%. I think I’d sell at that price, but would buy at 50%, which is a fancy way of saying, I think it’ll happen, but I’m really uncertain. How should we evaluate a new nuclear deal?

The Atlantic Council has laid out a grading rubric for any deal. I have a pass/fail one. Does it work out for the US better than JCPOA on the same time scale. I do have some optimism given Iran’s regional strength compared to 2015, but we’ll have to wait and see.

Post Scriptum

If you have learned a foreign language that you don’t use regularly, read something in that language a couple times each week. I used to have decent-ish Farsi skills, but let them atrophy. I didn’t realize how bad it was until I tried to read some Persian language sources for how their reporting on negotiations.

1. Isotopes are variations of the same element with different numbers of neutrons in their nuclei. It’s been quite a while since AP Chemistry, so I had to double-check this.

2. Iran Watch has a nice table on the estimates of Iran’s centrifuge counts.

3. That hasn’t completely stopped Israel from hampering Iran’s nuclear program. I would charge a very high premium if I offered life insurance policies to Iranian nuclear scientists. Israel and the US have also used sabotage to slow down Iran’s nuclear program.

4. Source for paragraph.

5. I’m not going to entertain the possibility that Iran’s nuclear program is for civilian uses only.

6. I haven’t read it yet. I’m probably going to re-read Arms and Influence before I do. I did watch an interview with him.

7. The ceasefire was possibly a way for Iran to lower tensions to get to a negotiation. This seems reasonable, but there is a possibility the Houthis decided to make a deal on their own. Proxies are not puppets.

8. Here is a good video on the subject.

9. Red lines aren't exactly red lines.