Edit 7/5 I think this piece was a bit overconfident—see Peter Wildeford’s comment for some reasons, though I think the conclusion is still likely correct.
Recently, America and Israel attacked Iran, hoping to set back Iranian nuclear ambitions. This is broadly in line with Trump’s consistent affinity for randomly attacking Iran. Despite his claims to be a non-interventionist, Trump is clearly an Iran hawk—certainly far more so than Biden.
In light of this shift towards the ‘set-things-on-fire’ strategy for stopping Iranian nuclear development, it’s worth thinking hard about what we had before. Before the recent era of saber rattling, Iran and the U.S. had an agreement in place—called the JCPOA—that was designed to stop Iranian nuclear ambitions. It ended because Trump pulled out of it, despite full and complete Iranian compliance with the deal. This was one of the worst things he did during his first term (other than attempting a coup!)
Expert consensus is rare in foreign policy. Getting foreign policy experts to agree is like getting Rabbis or philosophers to agree. Yet one of the issues where there is a genuine consensus is in support for the JCPOA. 94% of foreign policy experts opposed our decision to exit the deal. This is basically as high as consensuses ever get in any field!
So what did the JCPOA do? In exchange for sanctions relief, Iran had to do a bunch of things that set back Iranian nuclear ambitions. Specifically:
Enriched uranium is the main way to power a nuclear weapon. The JCPOA reduced Iranian enriched uranium stocks by 97%.
To make enriched uranium, one needs centrifuges. The JCPOA reduced centrifuge numbers by about 75%.
The other way to power a nuclear weapon is with plutonium made through a heavy water reactor. The deal required Iran to stop using that kind of reactor, and redesign the facility they had in Arak so that it could no longer be used to make plutonium of the right kind.
The deal required routine IAEA inspections.
Spent fuel reprocessing, a key ingredient in creating nuclear weapons, was shut down, and all spent fuel was to be shipped out of the country.
Iran was complying with each of those provisions. In exchange for this, Iranian assets were unfrozen and the U.S. got rid of sanctions on Iran. In Iran, it was the terrorists and the radicals who opposed the deal, and the moderates who supported it.
The main objection to the JCPOA is that it just kicks the can down the road. Those raising this objection claim that while it slightly delays Iranian nuclear ambitions, it doesn’t stop them. But this objection is misguided.
First of all, one only needs to look at how Iran behaved during the deal vs after the U.S. pulled out of the deal. When the deal was in place, Iran was not enriching uranium beyond allowable levels. After we pulled out, they began enriching uranium and are likely to continue, with the recent strike only briefly setting them back. We don’t have to guess how the deal was working—we can just look at Iranian behavior.
Second, even though the deal was temporary, it drastically delayed Iranian nuclear ambitions. As discussed above, it effectively eliminated all of the things Iran needed to build a nuclear weapon. As an analogy: if you start building a house, and we make a deal where you get rid of all the material you use to make houses and destroy the house in progress, that lowers the odds of you ever building the house. The JCPOA was similar.
This also raised the so-called breakout time. When the deal was in place, Iran had little of the relevant materials. Developing nuclear weapons from their depleted stockpiles would have taken a long time, allowing for a more effective American response. Now, Iranian nuclearization could be far quicker, providing less time to respond.
Third, another deal would likely have been negotiated after the first one expired. Iran only signed the deal because they cared more about sanctions relief than nuclear ambitions—if, indeed, they had any nuclear ambitions. After fifteen successful years of sanctions relief in exchange for delayed nuclear ambitions, Iran would be likely to negotiate another deal.
Fourth, even slowing down nuclear development is very good. Every year a country has nuclear weapons poses serious risks. Delaying Iranian nuclear development—and the potential proliferation cycles associated with it—majorly sets back risks. Who knows what the world will be like in 2030. Depending on how the Iranian regime changes, risks could be much lower.
Fifth—and this is probably the most important point—pulling out of the deal permanently jeopardizes any chance of nuclear containment. The Iranian nuclear deal showed other nations that America doesn’t take its word seriously. If a deal is negotiated, it might be vaporized on a whim by the belligerence of a president. In light of this, no country has any incentive to negotiate a nuclear deal with America in the future. When you break your deals, it’s harder to make new ones.
Sixth and finally, not all JCPOA provisions expire. The deal established a long-term IAEA presence in Iran and a reiterated commitment not to develop nuclear weapons. Thus, if Iran moved to develop nuclear weapons, the deal would make it easier to identify that ahead of time and stop them.
The end of the Iranian nuclear deal had five major costs.
First, it directly increased the probability of Iran developing a nuclear weapon. The odds are non-trivial that in a few years, Iran will possess a nuclear weapon. That nuclear weapon might be used against their enemies. This is a worrying prospect given the history of nuclear close calls.
Second, it placed strangling sanctions on Iran. Between 2012 and 2015, sanctions were responsible for a 15-20% reduction in Iranian GDP. In an already poor nation, crippling sanctions destroyed nearly a fifth of their economic output. Reintroduction of sanctions decreased Iranian GDP growth by a whopping 13 points, from 9.5% to -4.1%.
By conservative estimates, sanctions on Iran caused around 13,000 extra deaths during the pandemic alone. More than half of Iranians are malnourished, including children, and sanctions are one big reason for this. Delaying Iranian economic development increases the probability of them remaining impoverished and repressive for even longer. We need quite strong moral justification for us to decimate the economy of a starving and impoverished nation.
Third, by increasing the probability of an Iranian nuclear deal, ending the Iranian nuclear deal made broader middle eastern proliferation vastly likelier. If Iran gets nuclear weapons, Saudi Arabia and the UAE would want to follow suit. This could trigger a frightening escalatory spiral in the Middle East as more and more nations become nuclear-armed. A nuclear-armed middle east could pose a very serious threat to global stability.
Fourth, other countries might respond aggressively to stop Iran. Perhaps Israel would carry out a nuclear first strike. Even if this doesn’t happen, there could be a broader regional war as other nations try to strike Iran if Iran is close to developing nuclear weapons
Fifth, this lowers the odds of general nuclear-containment. Because the U.S. pulled out of the deal, other countries will not trust America to make a deal in the first place. This will hamper efforts to dismantle the North Korean nuclear arsenal, for instance, and to stop other countries from developing nuclear weapons.
Trump in his second term has done large numbers of obviously disastrous things. But during his first term, he was more restrained, and pulling out of the Iranian nuclear deal was one of the worst things he did. He did it because he wanted to swing his dick around about the profound toughness of his negotiations and because of the Republican party’s generally bellicose attitude towards Iran. It is alarming that such devastation can come from one man’s desire to send a signal and show strength!
I think nuclear containment is one of the most important elements of a good foreign policy. Nuclear war is one of the few ways the world might end, and preventing the end of the world ought to be our top global priority. But those who talk most aggressively about preventing Iranian nuclear development tend to be the most likely—by far—to bring about Iranian nuclear development. Senseless militarism is not a productive strategy.
It doesn't seem like you even tried to look up what opponents of the JCPOA were saying at all?
Under the sunset clauses Iran would have very little incentive in 2030 to enter a new deal. Yes, there were still US primary sanctions, so it's not like there would be no leverage at that point, but if Iran wanted to do exactly what it ended up doing (namely enriching a ton of uranium to 60% and becoming a nuclear threshold state) it could have done that even without withdrawing from the NPT and even under IAEA inspections. So the bet was always that by 2030 either the regime would be different, or it would have moderated. Obviously we don't know the counterfactual but given that we are now in 2025 I think it's a fair bet that that would not have happened. In addition, even before the pullout, it was clear that its behavior was not moderating in terms of its missile program or its support for proxies around the region or its core ethos of trying to destroy Israel.
From Israel's perspective, the missile program, building 10,000 ballistic missiles, was also viewed as an existential threat and so at some point Israel may have attacked in any case.