This past Saturday, US and Iranian representatives held indirect talks in Oman, and they are set to continue these discussions this weekend. What do you make of this development? Given that Iran is in a significantly weaker place than it was a year ago, how should the US approach these negotiations?

It’s good that there’s some diplomatic engagement happening between the United States and Iran on the nuclear issue, whether indirect or direct. It’s a little unclear whether that distinction even matters. In the last meeting, Witkoff apparently had a brief sidebar with the Iranians, which is a good thing.

Iran is in a weaker position now. Its proxies aren’t as strong as they used to be. Their response to Israel wasn’t as overwhelming or impressive as they may have hoped. That might have been intentional, or not. Hamas is obviously very weak. Hezbollah is essentially in tatters. The Syrian regime is effectively gone.

But the fundamental questions around the nuclear issue haven’t changed much in the last 15–20 years. Iran has mastered the technology to produce nuclear fuel that could be used in a weapon. It's still unclear how close they are to being able to weaponize that material and developing a delivery system, if they chose to do so. Iran has, at least until recently—and maybe still today—liked being perceived as a threshold nuclear state. I’ve always believed that Iran may not actually want a nuclear weapon, because that comes with major risks. But they do want to be seen as capable of quickly acquiring one, which gives them leverage—against Israel, the Gulf states, and others.

Have those dynamics changed? Probably not much. The only major shift is that under the Iran Nuclear Deal (the Joint Comprehensive Plan of Action, or JCPOA), Iran was constrained in how much nuclear material it could produce and stockpile. When the Trump administration left the deal, and Iran responded by walking away from its own commitments, all of those constraints evaporated. Stockpiles increased, enrichment levels rose, and so on.

Now the conundrum is where to start. Do you focus again on capping the amount of nuclear material Iran has? Or do you try to tackle the harder question—can you verify and constrain the weaponization aspect? Have they figured out how to assemble the other components of a weapon beyond just the uranium? Or do you focus on something else entirely, like missiles, which has always been elusive?

Witkoff’s initial approach was smart: get in the room and talk it through. Yes, we have a starting position, but that’s the point of negotiations—to work toward something attainable.

Over the weekend, he seemed to shift more toward the Waltz position: dismantle both the enrichment and weaponization programs. My bias is clear. I worked on the JCPOA and thought it was very effective. At the very least, it delayed these kinds of issues. If we had kept the JCPOA in place, these questions about stockpiles and enrichment wouldn’t be showing up until now, instead of eight years ago. We would have had more time to think about a follow-on deal.

Now we’re either trying to resurrect an old deal or risk settling for something less effective and less verifiable. Either way, it’s positive that meetings are happening. I still believe the most effective way to constrain Iran’s nuclear program is through a negotiated deal. A military solution, in my view, is like weeding your garden: you can pull some things out, but they’ll grow back. And next time, Iran will be better at hiding what it’s doing, making it harder to monitor. Plus, a strike would embolden hardliners in Tehran who’d say, “Now we really do need a nuclear weapon.”

I hope negotiations are successful.  A new deal has to be verifiable, and it has to involve the IAEA in a way that gives the international community confidence that whatever limits are agreed upon are being respected.

The New START Treaty is set to expire in 2026.  How do you assess the prospects for renewing arms control talks with Russia, particularly in light of recent mixed signals from Moscow? Are bilateral negotiations an opportunity that the U.S. should take if given the opportunity?

Arms control is always worth pursuing, as long as it contributes to stability on both sides and is verifiable. The New START treaty is set to expire in less than a year. Overall, it would be positive for us to find a way to negotiate a follow-on agreement. The challenge is that current and previous nuclear arms control agreements have historically taken a long time to negotiate. If we’re just getting started now, it’s unclear whether we’ll have enough time to put something in place, especially if it’s a treaty that would need ratification by the U.S. Senate—and presumably also by the Duma in Moscow. That said, I suspect it’s probably easier to get something through the Duma if Putin supports it than to get it through the U.S. Senate. Still, it’s worth pursuing.

There are going to be several challenges. First, the situation has changed dramatically. Since the dawn of the nuclear age, every major arms control agreement has focused on bilateral controls between the U.S. and the Soviet Union, and later Russia, because we were the two dominant nuclear powers. Other countries were secondary. But the growth of China’s nuclear program has fundamentally altered that dynamic.

When I was in the previous administration, during our Nuclear Posture Review and related policy statements, we made it clear that this shift is a major change. Any future arms control agreement would have to account for the growth in Chinese nuclear forces. That doesn't mean we can’t reach another agreement, but China’s role would have to be considered.

Additionally, the ratification of New START came with expectations from the U.S. Senate and leadership that any follow-on agreement with Russia should address not only strategic systems but also non-strategic, or tactical, nuclear weapons. Both the Trump and Biden administrations have attempted to include all nuclear warheads in a future agreement. It's unclear whether the Russians would agree to that, or what the details would look like.

While an agreement is worth pursuing, as of now, Russia has essentially refused to engage. Not only have the Russians declined to begin new negotiations, but they've also avoided participating in the Bilateral Consultative Committee for the existing treaty.

The President’s recent statements might help, and figures like Peskov or Sergei Ryabkov—the Deputy Foreign Minister—have suggested that the tone from the new U.S. administration is less combative, which could open the door to talks. But it's still a challenge.

Finally, there’s been talk in the arms control community about a voluntary extension of the current treaty to buy time for a new agreement. That’s a nice idea in theory, but it has to be balanced with the fact that the U.S. nuclear modernization program is ongoing. A simple extension of existing caps might not align with when new systems come online or old ones go offline. The planning and numbers get complex very quickly—likely for the Russians as well. While a short-term extension might be feasible, maintaining the current cap long-term would probably require new negotiations.

What effects will an accelerating US-China trade war and deteriorating economic relations with states in the Indo Pacific have on the U.S. deterrent posture in the region? Do these tariffs play any role in nuclear politics? How we deal with and assure our allies in the region (Japan, South Korea, Australia), or how we deter China?

The Chinese are masters at connecting seemingly unrelated issues into a single narrative. I vividly remember a trip of mine being canceled at the last minute. I was supposed to accompany my boss to discuss nuclear nonproliferation issues, but the trip was called off because President Obama had met with the Dalai Lama. What the Dalai Lama had to do with sanctions on Iran, I couldn’t tell you—but in the Chinese system, that was leverage. They used that meeting as justification to block engagement with the U.S. on unrelated matters.

For many years, across administrations of both parties, the U.S. government has often tried to separate certain topics—especially those we see as vital to national security—from other political tensions. But that’s becoming harder. Take the New START treaty as an example. Even during the Cold War’s darkest days, the U.S. and the Soviet Union still managed to engage in arms control and strategic stability talks. They weren’t always successful, but the dialogue was rarely cut off entirely. Now, however, Putin is directly tying those issues to Ukraine. Similarly, I wouldn’t be surprised if the PRC starts linking issues like tariffs to security-related talks.

And honestly, the Chinese haven’t been eager to engage with the U.S. on these topics to begin with and so they don’t need much of an excuse to avoid those conversations.

The second half of your question is possibly even more important. In recent years, we’ve focused on reassuring our allies in Northeast and Southeast Asia that the U.S. is an Indo-Pacific power, that we will be there for the long haul, and that we are committed to being a reliable partner. While we hope for areas of cooperation with the PRC, there will inevitably be competition. We’re not seeking confrontation, but strategic competition is a reality.

From the perspective of our allies, if the U.S. starts to appear less reliable—whether in terms of trade, defense, or extended deterrence—it could raise serious concerns. For example, if we impose high tariffs on an ally, they may ask, “Is this what friends do? Can we count on the U.S. when it comes to our defense relationship or other strategic partnerships?”

This will have an impact. Tariff news changes daily, so by the time this interview is published, the situation could be completely different.

I hope the administration continues to focus on maintaining and strengthening extended deterrence, especially with Japan and South Korea. So far, the Trump Administration has been very positive on this front and has made strong statements of support. The meeting between President Trump and Prime Minister Ishiba was very productive. They haven’t had that same level of engagement with South Korea yet, due to political turmoil there. With a new South Korean president expected soon, I hope for similarly strong dialogue.

Overall, I give both President Trump and Prime Minister Ishiba a lot of credit for fostering what appears to be a solid personal relationship.

Since the end of the Cold War, the U.S. nuclear umbrella has remained intact and the nuclear nonproliferation regime has largely held. Do you think this stability can continue, especially given the current strains in the transatlantic alliance? Are we likely to see more countries seriously reconsidering moving forward with building nuclear weapons?

This has been an issue even before the Trump administration. The South Koreans’ concern over whether they should have their own indigenous nuclear weapons predates Trump and was something the Biden administration dealt with too.

Similarly, these discussions have been happening in Europe and NATO internally. In my previous role, when I was going to NATO frequently and meeting with our European allies, there were discussions about the U.S. clearly identifying the PRC as the pacing challenge. The question came up: if the U.S. is focused on the Indo-Pacific, what happens if there's a conflict in the Western Pacific? Will the U.S. still be there for Europe?

That led to positive discussions. Were there more things Europe can do? This has been a bipartisan issue. While the style has differed, both parties have held the position that Europe should do more to defend itself and invest in its own defense, including within NATO.

What has changed is how much more out in the open this conversation is now. The rhetoric has escalated, and there are concerns that these changes might happen more quickly than expected—or that Europe hasn't prepared adequately. And frankly, they should have been better prepared. Multiple U.S. administrations have been telling the Europeans that they need to step up. What does this mean for extended deterrence?

First, I understand the concerns about the state of the Non-Proliferation Treaty (NPT) and the potential for new states acquiring nuclear weapons. I share that concern. But there are technical realities. It’s not as simple as just deciding to build a nuclear weapon. Even countries with advanced nuclear technology—like South Korea, Japan, or historically, Germany—can’t just flip a switch. Even if they reenter the nuclear space after abandoning it, there are still significant steps involved.

Many of these decisions would be noticed. There would be multiple opportunities for dialogue, reassurance, and diplomatic tools to be used to discourage such choices. In fact, having nuclear weapons could increase a country's risk of being targeted in a nuclear attack.

Take South Korea, for example. If the government were to announce a move toward nuclear weapons—or even pursue them clandestinely—there could be consequences. They might lose certain alliance protections or access to technologies due to export controls. There could be a gap between losing the U.S. nuclear umbrella and acquiring their own weapons. That’s a dangerous moment for the South Koreans. If the U.S. is no longer protecting them and they don't yet have nuclear weapons, they’re vulnerable. It’s easy to say, "let’s just get nuclear weapons and be independent," but the practicalities, timelines, and legal implications make it far more complicated.

And despite concerns about the strength of the NPT—which again, I do share—it has been a remarkably resilient framework for decades. In the early Cold War, there was an assumption that dozens of countries would eventually acquire nuclear weapons. If you look at some of the declassified memos from that era, those predictions never came to pass. The NPT played a key role then, just as it does now. We need to stay mindful of its continued importance.

At the same time, we must continue finding ways to reassure our allies that they don’t need to pursue nuclear weapons. Some of these efforts are already underway with South Korea and Japan, and some were initiated by the previous administration. I believe the current administration should not hesitate to continue those efforts. This is really a bipartisan—or even nonpartisan—approach.

Regarding Europe, the Administration's position that Europe should do more is not necessarily wrong. The key question is how. In my view, the answer lies in doing more on the conventional side: investing in conventional deterrence that can counter the likelihood of a Russian attack.

At the same time, we should look for ways to better integrate European conventional forces with U.S. nuclear planning and posture—without necessarily putting nuclear weapons in countries like Poland. Instead, maybe Polish pilots, or Norwegian or Finnish pilots, could be trained to fly nuclear missions if needed. That doesn’t mean moving nuclear weapons into those countries or them acquiring their own, but it could deepen integration and offer reassurance that the U.S. nuclear deterrent still extends to them.

What guidance would you offer the new Trump appointees that are being approved by the Senate and as positions are being filled coming in, who will be working on nuclear security and CWMD policy? 

I know some of the people who are coming in, and there are still some positions yet to be filled. The good news is that many of them are highly qualified and knowledgeable on these topics, so they don't necessarily need my advice.

That said, the best advice I can offer is to recognize that we’re in a very dynamic environment right now. It’s important to stay aware of everything happening globally and keep that broader perspective in mind when shaping policy and posture in this new, more complex era.

One of the challenges in government is how slow it can be to implement change—especially if it involves more than just signing a piece of paper. The analogy often used at the Department of Defense is that it's like turning an aircraft carrier: it has tremendous power, but it takes time to pivot.

Given the pace of global change, we need to think not only about today but about what the world might look like in 10, 20, or even 30 years. That means investing now in strategies that keep us on the cutting edge and able to defend against future threats. This includes emerging technologies like artificial intelligence, which will likely become a major part of our lives sooner than many expect.

These technologies hold enormous promise for positive impact—such as improving defense capabilities or enabling rapid development of medical countermeasures against biological or chemical threats. But they also carry the potential for serious harm, whether through deliberate misuse or unintended consequences. That dual-use nature demands thoughtful planning.

In a way, it's similar to the conversations around nuclear technology in the 1950s and 1960s. There was huge potential for good, like nuclear energy, but also grave risks if weaponized. The same is true for AI today.

I know many people in government are already thinking about these issues, and it's important to maintain that balance. My advice to the incoming team would be to think long-term. That’s difficult in government, where you’re often focused on the next 72 hours. But taking the long view will ultimately benefit both current leadership and those who follow.