The pillars of the global nuclear order are crumbling. Earlier this month, New START, the main nuclear treaty between the United States and Russia, expired; China has been rapidly expanding its nuclear arsenal; and in keeping with a general state of geopolitical flux, several other countries are now discussing the possibility of acquiring history’s deadliest weapon.

On the latest episode of FP Live, I spoke with Rafael Grossi, the head of the International Atomic Energy Agency, or IAEA—the United Nations’ nuclear watchdog. Grossi has been at the forefront of monitoring the safety of Ukraine’s nuclear power plants—even under Russian fire. And for years while the IAEA still had access, he oversaw the international campaign to keep an eye on Iran’s nuclear program. Armed with his home country Argentina’s nomination, Grossi is considered to be among the front-runners to be the next secretary-general of the United Nations.

I spoke with Grossi over the weekend on the sidelines of the Munich Security Conference. Subscribers can watch the full discussion on the video box atop this page. The interview will also run on the free FP Live podcast. What follows here is a lightly edited and condensed transcript.

Ravi Agrawal: I want to begin with New START. This was the nonproliferation treaty between the United States and Russia, the world’s two biggest nuclear players. How worried are you that the treaty has expired?

Rafael Grossi: It was a well-known secret that it was going to happen. In the immediate future, there will not be any big changes. The impact of this is more that we don’t have, at the moment, any other arms limitation treaty to set a maximum number of warheads and things like that. Nobody is expecting to see a dramatic change in nuclear arsenals in the immediate future, but it’s important that the issue continues to be looked at. Despite their limitations, these instruments provide an element of predictability in general and strategic terms as to where big nuclear powers stand.

As you know, there is a push from the United States to include other actors like China in the discussion. China is not in agreement with that. But in any case, there are also new technologies now—vectors and hypersonic submarine drones—that would need to be included for an instrument to be effective.

RA: Much of what you’re saying is similar to U.S. President Donald Trump’s position. But part of the issue is that there doesn’t seem to be sustained movement to create a new treaty.

RG: I’m not privy to the discussions, but I think the United States and Russia are talking. So perhaps it’s not completely accurate to say nothing is happening. There is a dialogue, and of course it should be promoted and supported.

RA: You hinted at this earlier, but there’s vertical proliferation, when a country that is already a nuclear power expands its arsenal, and there’s horizontal proliferation, when new countries acquire nuclear weapons. Nine countries have nuclear weapons now, and the IAEA says that there are about 30-plus countries that could be ready to join that nine-member club. So, is horizontal proliferation more worrying, in a sense?

RG: I think it’s a new factor. We always knew it could happen; it was the basis for the push that drew us to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), to try to contain the phenomenon. But technologically speaking, we know that a number of countries could theoretically be in a capacity to move into this sphere. And we see that now in public discourse—countries that up until now were in good standing with the NPT are saying they might need to revisit their position vis-à-vis the possession of nuclear weapons.

This is a very disturbing trend. We can look at vertical proliferation to see that the big powers contain certain amounts of warheads, systems, and deployments. But when you start to spread these things… [pauses]

The NPT system has been working, albeit imperfectly. There is a certain limitation. Being outside the circle has important costs, and there are just a handful of countries that remain outside the NPT and have different rationales for having nuclear weapons. But with the current degree of fragmentation, and with the rise of geopolitical confrontation, to all of a sudden be confronted with a world where we will have 20 countries with weapons, we are sure to see nuclear use, even in regional or subregional conflicts, with the potential of escalation.

RA: To be counterintuitive, there is a case to be made that nuclear weapons could ensure that countries actually de-escalate more quickly.

Last year, when India and Pakistan had a brief four-day war, one of the reasons why it didn’t continue and turn into a long, grinding attack was that both sides knew they could easily escalate with nuclear weapons, and that pulled them back from the brink. Ukraine would argue, for example, that if it did have nuclear weapons, then it wouldn’t be stuck in a war that is now nearly four years long. When you hear that argument, does it not strike you that maybe the nuclear club should expand?

RG: Not at all. I don’t think adding countries with nuclear weapons will add to common security in any way. I can follow your logic, and it’s compelling in a certain sense, but in some of the current conflicts, the existence of nuclear weapons might precisely lead to their use. If you have a nuclear country in a region, then the perceived rival will go for it immediately, and this will spread in an uncontrollable way. It happened in the Indian subcontinent [with India and Pakistan].

The incentive is to “keep up with the Joneses,” as the Americans say, and have what their neighbor has. If my neighbor has a nuclear weapon, then they can do whatever they want at the border, in the seas, with fisheries and natural resources—so we would be entering into a slippery slope, which should be avoided. The cases that we have at the moment, albeit controversial, are well-understood in certain regional contexts. The ramifications of a free-for-all, while knowing the degree of technologies that exist there—would be terrible.

RA: Right, and it could fall into the wrong hands. I want to put a pin in this debate on proliferation and come to Iran, which is a signatory of the NPT. Before the 12-day war last year, in which the United States and Israel attacked Iran’s nuclear facilities, the IAEA released a report citing Tehran’s failures to uphold its obligations under the NPT. Can you give us a sense of what you found troubling in that report?

RG: Thank you for mentioning this, because some, after what happened, blamed the IAEA or me personally.

RA: You’ve been accused by the Iranians; you have a target on your back.

RG: It’s interesting, because that same report said that we did not have any information that would indicate that Iran had or has a program to develop nuclear weapons. We were not ill-intentioned or in collusion with someone to wage war against a country—which would be absolutely absurd from every possible angle—because the IAEA has to be objective and tell it as it is. We were saying that on the one hand, there’s nothing that indicates that they are going that route, but at the same time, there are all these factors which are reason for concern. We were asking Iran to give us full access.

RA: And they hadn’t been.

RG: Of course not. We had access to some things, but there were a number of things that we had discovered—traces of enriched uranium in places that were not linked at all with the nuclear program. Obviously, something had been hidden. So there were a number of questions, but what happened, happened. We cannot rewrite history. The IAEA has always been extremely objective. The reality is that we were painting the full picture.

RA: Paint some of that picture for our viewers and listeners. Israel would ask Iran, why do you need to enrich uranium up to 60 percent? They claim you only do that if you intend to turn that into a bomb. The Iranians will say they have no desire to get to a bomb, and if they wanted to, they would have done it yesterday.

When you look at what they were doing before the 12-day war—and you had the best sense of reality on the ground—where did you come out on this?

RG: It is clear that the accumulation of highly enriched uranium at this level, while not forbidden in itself, was raising lots of questions, because there was no clear, immediate, practical use to it. That, combined with all these unanswered questions and limitations, was raising flags. Now, the situation is different. Things have changed, because there was a war.

RA: A lot of this is mired in confusion. President Trump, after the 12-day war, said that Iran’s nuclear facilities were “obliterated.” Then there was a leak from the Pentagon suggesting that this was premature, and that maybe Iran was able to save some of its nuclear facilities. There’s also the separate question of what actually happened to the uranium. Where do things stand now?

RG: The war has been a watershed, because the physical damage to the infrastructure has been very big, meaning that what was attacked is not operational anymore.

RA: So the centrifuges don’t work.

RG: My inspectors have not been able to go there and to see the damage, but we know these facilities very well, and by the simple projection of what happened—the amount of power used during the attack—the consensus is that the capabilities that they had do not exist anymore.

It doesn’t mean that everything has been destroyed. You don’t unlearn what you have learned, and Iran has the technical and industrial capability to reconstruct this infrastructure if they so wished. We don’t see this happening now, but it is something that has to be taken into account. They have mastered the technology for highly advanced super centrifuges.

RA: And if the program were being rebuilt right now, would you know, at this point?

RG: No, because we are not getting access to these places. This is why, among other things, it is so important that we regain this access. And there is the other element: The nuclear material is still there.

RA: Do you know how much?

RG: By the last account, around 440 kilograms of 60 percent enriched [uranium], and even bigger amounts of 20 percent and 5 percent. So there’s a big stockpile of nuclear material, especially the 60 percent. We need to go back to check that this is not diverted or being hidden somewhere.

I think Iran understands that we need to go back, and we are having this discussion. The complexity is that there is an implicit relationship between this and the ongoing negotiations—or consultations, or conversations—with the United States, which is very important.

RA: Let’s look at the full picture. There were talks recently in Oman in which the United States had a broader range of requests. It was not just nuclear. They also wanted Iran to take its ballistic missiles off the table and stop funding various militant groups in the region. Iran has said those two things are not up for debate, but it’s happy to talk about the nuclear issue. [Editor’s Note: The second round of talks in Geneva ended on Tuesday with the Iranian foreign minister announcing an agreement on “guiding principles.”]

Meanwhile, the United States is moving military assets into the region, probably a form of coercive diplomacy, probably an increased likelihood that the United States might attack anyway. Given all of that, what’s your sense of the chances of diplomacy working here?

RG: It’s a very discreet process taking place at the moment, where both sides are trying to define a place of convergence. This is not easy, obviously, because what is at stake here is the fate of this material. More importantly, projecting into the future, it’s about what the nuclear program of Iran is going to look like, so that we can find some stability and that the United States and others are content and do not see a risk of proliferation, under the strict verification of the IAEA.

RA: Let me zoom out to the bigger question about proliferation right now. There is a sense around the world—and it’s very clear here at the Munich Security Conference this week—that countries feel like America is less reliable than it used to be. On the nuclear front, you see that play out when, for example, there is talk of South Korea or Japan going nuclear, or when Saudi Arabia signed a defense pact with Pakistan, a nuclear power, which includes some form of a nuclear umbrella.

When you look at the world right now, how concerned are you that countries are seeking their own nuclear umbrellas?

RG: It’s a very important point that you’re raising here, because one can understand the logic of those who are looking after their national interest. They feel they need the degree of protection that nuclear weapons might give. But as we were saying earlier in the conversation, that’s not the way. Adding nuclear weapons to countries would be tantamount to unraveling the world nuclear order as we know it, with all its imperfections.

Please don’t misunderstand me. I am not pretending that this is perfect. But throwing this away to plunge into a free-for-all, each one fending for itself, would be a dramatic mistake.

RA: You are in the running to be the next secretary-general of the United Nations. Your country, Argentina, has nominated you. There’s a consensus right now that the U.N. isn’t working well, that it’s divided, it’s polarized. Some would just call it broken. Why do you want the job?

RG: Precisely for what you said. Because I don’t think seeing the United Nations in this state is in anybody’s benefit. There is frustration, cynicism, and criticism about the U.N., which is not at the center of any peace and security process.

But there is a big plus that the U.N. has: Everybody agrees that if it did not exist, we would have to invent it again. Because all these platforms that we have—BRICS, the Shanghai Cooperation Organisation, the G-7, the G-20, and all of these groups, which are very, very important—they still lack the glue of a global platform which only the U.N. can provide.

I approach this from my own experience. When you look at the IAEA, you see a multilateral agency that is respected. It provides a service for peace, security, nonproliferation, and energy. That is, even in these very difficult circumstances, a viable vehicle for peace diplomacy. I am able to talk to [Russian] President [Vladimir] Putin, to talk to [Ukrainian] President [Volodymyr] Zelensky, to talk to Iran, even when they are threatening us, and to talk to the Americans.

We are doing exactly what has been missing. I believe in multilateralism, in diplomacy as a way to solve international conflicts. This next election of the secretary-general, in my opinion, will be one of the most consequential. There is a need for something different, for a change.