How is Trump changing America’s extended deterrence regime? I got Polymarket to make a market on whether a US ally will acquire nuclear weapons in 2025. It’s currently trading at 6%. Are we buyers or sellers?
To discuss, I interviewed Vipin Narang, professor at MIT, who served as Acting Assistant Secretary of Defense responsible for nuclear deterrence policy during the Biden administration; Pranay Vaddi, a senior fellow at the Center for Nuclear Security Policy at MIT who worked on arms control and non-proliferation on Biden’s National Security Council; and Junichi Fukuda, senior research fellow at Tokyo’s Sasakawa Peace Foundation.
We get into…
The historical development of the American nuclear umbrella, including the “software” and “hardware” components of deterrence,
The probability that an American ally will proliferate by 2030, and which countries are the most likely candidates,
Why France proliferated despite US objections,
How the world might respond to nuclear ambitions from Poland, Japan, or Saudi Arabia,
China’s nuclear modernization and deterrence strategies for a multi-polar world.
Listen now on iTunes, Spotify, or your favorite podcast app.
Thanks to the US-Japan Foundation for sponsoring this episode.

Foundations of Non-Proliferation
Jordan Schneider: Let’s start with a history of American extended deterrence. Where did this concept originate, and what has it achieved over the past 75-plus years?
Vipin Narang: Extended deterrence is the notion that the United States will use its range of capabilities — including nuclear weapons — to defend its formal allies and partners against nuclear attack from a common adversary. It also covers high-consequence non-nuclear strategic attacks, which is a mouthful but really means an existential threat to our allies.
The concept developed in the mid-1950s after World War II. European states had been devastated by the war and could not defend themselves against the emerging Soviet threat. The United States maintained its forward conventional deployment, but our huge advantage over the Soviet Union was nuclear weapons. The Eisenhower administration quickly realized that against a conventionally superior Soviet Union, we might need to increasingly rely on nuclear weapons to defend our forces and our allies, which were still rebuilding.
We never implemented extended deterrence out of altruism or charity. It benefited the US by preserving the openness of Western Europe and our East Asian allies, particularly South Korea and Japan, after the Korean War and World War II. This allowed us to keep the economies and political systems of our allies free, democratic, and capitalist, which created open markets for the US.
Over time, extended deterrence became important for another reason that is often overlooked — it became our best non-proliferation tool. We could prevent our allies from pursuing their own nuclear weapons if they believed our nuclear umbrella would credibly deter common adversaries. Kennedy predicted that we’d have 25 nuclear weapon states by the end of the 1960s — that was largely prevented by a credible extended deterrence architecture that the United States developed and maintained.
We worked with allies not just to deter common adversaries — China, Russia, North Korea — but to assure allies that we would come to their defense. Making this credible requires convincing allies that we can fight on their behalf without losing American cities or allied cities. The core of making extended deterrence work is being able to substantially limit the damage that Russia or China can impose on both the ally and the US homeland.
Regarding the non-proliferation point, extended deterrence has a remarkable record of preventing ally proliferation. Of our 34-35 formal allies, France is the only state that consciously decided to acquire nuclear weapons because it believed the US umbrella wasn’t credible for France’s defense. We can discuss some corner cases, but France remains the only example where perceived lack of credibility in extended deterrence caused a formal ally to develop nuclear weapons. Until now, it’s only been one case, and we hope it remains that way.
Jordan Schneider: Let’s explore this “Berlin-for-Boston” dynamic. The assumption throughout the Cold War and after was that no president would really trade Boston for Berlin. What was needed was a defense deterrence package that could plausibly threaten to keep Berlin free while avoiding an escalatory spiral that would leave Cambridge, Massachusetts in thermonuclear flames. What strategies has the US used over the past 75 years to make deterrence credible both to Moscow and to our friends in Asia and Europe?
Pranay Vaddi: You can’t separate the military dynamics and strategy from this discussion. What matters is the relationship between the head of state in the United States — the nuclear guarantor — and the head of state in the allied country receiving the nuclear umbrella. They need to be aligned. There must be a close political relationship between the United States and the 35 allies that Vipin referenced as nuclear umbrella allies.
When you put that relationship at risk or question whether the US will honor its defense arrangements — for example, if the United States declares at the presidential level it won’t defend an ally unless that ally spends a certain percentage of GDP on defense — it creates problems. Regardless of whether the United States maintains its nuclear modernization program, keeps forward-deployed dual-capable aircraft in Europe, or shows off B-2 bombers every time North Korea tests a missile, these mechanics can continue. However, every ally knows that it’s the US President who decides whether to use nuclear weapons in defense of an ally.
When the US President isn’t committed to an extended deterrence strategy as we have been for the past 70-80 years, it creates doubt. This is what we’re seeing today — countries wondering if the US will actually honor its guarantees. Because of these doubts, Poland and South Korea in particular have started discussing how to hedge against potential US abandonment of nuclear guarantees.
Just this week, we’ve seen continued statements from French officials about what a European deterrent could look like — something that Vipin and I have written about extensively. Poland has indicated it would welcome both US and French weapons. But ultimately, you need to combine military strategy with political relationships.
One example of this approach is when Vipin and I, in our previous roles, worked closely with South Korean counterparts to establish the Washington Declaration at the presidential level when President Yoon visited Washington in April 2023. This required extensive work below the surface — Vipin leading discussions at the Defense Department with his counterparts in South Korea’s Ministry of Defense, alongside White House interactions with the presidential office in Seoul. The goal was to create public language that both countries could agree to, demonstrating a renewed and enhanced commitment to extended deterrence with commitments from both sides.
South Korea needed to recommit to the Non-Proliferation Treaty, while we needed to recommit to South Korea’s defense. We agreed to do so more transparently, giving South Korea greater insight into US nuclear planning and more input into how nuclear operations could be conducted. We needed to address both military and political aspects to provide reassurance in that bilateral relationship.
Jordan Schneider: Let’s stay on history a little more. We’ve got the credible military component — “I can actually bomb places” — and we’ve got the credible political aspect — “I actually care about your country enough to do something if it gets attacked.”
Vipin Narang: We called it “hardware” and “software.” The hardware piece is actually easier because it’s about having flexible capabilities to limit damage to the ally and the homeland. The theory is relatively simple, but implementation is not. This is something the Department of Defense spends considerable time contemplating.
Pranay’s point is really important — we underemphasize the importance of the software piece both historically and today. The only change from the Biden administration to the Trump administration is the software piece. That alone explains why we’re having this podcast. It’s almost like a blue screen of death for some allies. They don’t question our capability — they question whether, when the time comes, we will actually attempt to limit damage to the ally and US homeland and fight on their behalf.
Jordan Schneider: Let’s explore the history a bit more. What have been the sketchiest software moments since 1950?
Vipin Narang: The Eisenhower administration raised concerns right out of the gate. The plan was to reduce our conventional footprint, but that conventional presence in Western Europe reassured allies because we had skin in the game. Without skin in the game, the fear was we wouldn’t pull the trigger if the Red Army came crashing through.
The debate during the transition from the Eisenhower administration to the Kennedy administration centered on whether we had flexible enough options for a theory of escalation management. There have been various ups and downs, but what we’re seeing today is new: questioning whether we even care about our allies. Article 5 is a hallowed pillar of NATO and essentially our commitments to South Korea, Japan, and Australia.
For the first time, we’ve had an administration that basically says we might not honor Article 5, and allies might be on their own if they don’t pay enough. One of the bigger implications of the Signal chat leak was revealing that in private, the Vice President essentially said, “I hate Europe.” If I were Europe, I might question the willingness — not the ability — of the United States to step in when necessary.
Junichi Fukuda: Regarding the crisis of extended deterrence, we should consider the case from the early 1970s and late 1960s. At that time, the Guam Doctrine, or Nixon Doctrine, resulted in conventional forces withdrawing from the Indo-Pacific area alongside the withdrawal from the Vietnam War. This created a genuine crisis.
There was no clear nuclear extended debate then. Most countries were deciding whether to sign the Non-Proliferation Treaty (NPT) around 1969-1970. At that time, the Japan-US alliance didn’t explicitly mention the nuclear umbrella. The term “nuclear umbrella” was first used in 1975, yet Japan decided to sign the NPT during détente. The tension between the US and Soviet Union had decreased, allowing us to join the NPT.
Officially speaking, there was no extended nuclear debate at that time. This provides an analogy for our current situation — the United States withdrawing forces while the credibility of extended deterrence appears to be in crisis. We must learn from the experiences of the early 1970s.
Jordan Schneider: Perhaps the distinction between then and today was détente. You didn’t really see nuclear war on the direct horizon. China was busy with its Cultural Revolution, and the Soviet Union was being friendly. It wasn’t the most frightening period in thermonuclear history. Does that change the dynamic compared to today?
Junichi Fukuda: Because it was the détente era, tensions were reduced, so we didn’t have to deeply consider the implications of the extended deterrent crisis — we simply accepted it. In our current situation, US-China relations have deteriorated, and US-Russia relations are poor. Tensions are increasing while the United States appears to be withdrawing its engagement with the outside world. This creates a crisis.
Pranay Vaddi: Another historical element worth mentioning — something I always try to write about when Vipin and I collaborate, though he always deletes this paragraph — concerns extended deterrence from the early 1960s. There’s an interesting story about when a German Chancellor visited JFK after his White House victory.
Konrad Adenauer represented the CDU — the center-right in West Germany — and was essentially JFK’s opposite. Adenauer was about 85 years old while Kennedy was this young, new president. Kennedy was deeply concerned about allied proliferation, as Vipin outlined regarding developments in the 1950s and 60s.
According to declassified documents recording their meeting, Adenauer essentially said, “I hear you have weapons in West Germany, but I’ve never seen them. I’ve been repeatedly told those warheads are there, but I haven’t been shown them.” He wanted his Defense Minister to understand what the US was actually doing in their territory — what they had based there.
Kennedy assured Adenauer it made sense and promised that Defense Secretary Bob McNamara would brief him and his defense minister on the US stockpile operational plans — when we would actually use them if the Warsaw Pact attacked.
To me, this marked the beginning of the types of requests we in the US Government would regularly hear from allies — “What are you actually doing in a nuclear scenario?” As mentioned regarding the Washington Declaration and US work with South Korea, Japan, and NATO, we conduct tabletop exercises, scenario-based discussions, and simulations to demonstrate that the US has thoroughly considered extended deterrence scenarios. This marries hardware and software to make extended deterrence effective. Its origins date back to that conversation.
Retrenchment vs Burden Sharing
Jordan Schneider: If we’re using a relationship analogy, we’re saying, “We’re going to give you a tour of our place. We’ll let you bring some toothbrushes into the bathroom.” The US has been doing this 75-year dance with its allies, broadly trending toward reassuring everyone so they feel safe and secure enough not to develop their own nuclear weapons.
The question now is, what does the decay function of that look like? The Trump administration isn’t going to destroy our B2 bombers anytime soon, so the capability isn’t disappearing. However, the trust has developed some real hiccups, particularly on the software side.
Where do we start with this? What’s the right conceptual framework to understand the signals that the Trump administration is sending to the world?
Vipin Narang: Let me quickly address the hardware aspect. We shouldn’t overlook the hardware adjustments that were ongoing or being laid as a foundation at the end of the Biden administration. This includes ensuring the modernization program for each leg of the nuclear triad — we’re replacing each leg simultaneously for the first time in history, and we’re facing challenges.
The Sentinel ICBM is facing delays. Attention and focus are needed to prevent the modernization program from falling further behind schedule. The current administration hasn’t issued an executive order on nuclear forces, though it has addressed missile defense architecture, which is related but represents a very long-term strategy.
The immediate concern is our progress on this modernization program and how we’re dealing with China’s emergence — something we didn’t anticipate when we sized the modernization program 15 years ago. We don’t need forces matching the combined strength of our adversaries, but we might need more than what we planned when discussing New START numbers in 2010. At that time, Russia was considered a partner, and China and North Korea hadn’t begun their expansions.
For an ally examining the hardware aspect, there are mixed signals. The president has stated he doesn’t want to allocate more funds to nuclear weapons, which might be concerning. However, the more pressing issue, as Pranay and Fukuda-san mentioned, is that the software component isn’t experiencing a decay function — it’s a complete discontinuity. The posture toward our European allies has transformed dramatically since early January 2025.
If I were in the Indo-Pacific region — and I’d welcome Fukuda-san’s thoughts on this — there’s considerable uncertainty. The administration has declared China the pacing threat and pledged to focus on China, yet simultaneously continues to pressure Japan and South Korea economically in ways that may undermine the credibility of our commitment to defend them against existential threats from China or North Korea. This credibility is arguably much weaker than it was in January 2025.

Pranay Vaddi: The fundamental question is whether this is about right-sizing burden-sharing between the United States and its allies or pursuing a retrenchment ideology. If you’re an ally like Japan, you can approach the United States saying, “We understand you want everyone to pay their fair share. You want Japan to prioritize China as your primary concern, and we’re contributing to the extended deterrence strategy that Indo-PACOM needs for a Taiwan Strait crisis."
Japan is developing air and missile defense capabilities, long-range conventional strike capabilities, and a blue-water navy. They’re willing to open their shipyards for replenishment and repair of US naval vessels. In return, the US needs to maintain a strong nuclear umbrella and guarantee. That’s the basic exchange, but we should develop this strategy together.
If it’s primarily a burden-sharing question from the US, that’s a strategy to present to the White House: “Let’s determine the appropriate payment amount and capabilities within a bilateral strategy — or trilateral if South Korea is included, or quadrilateral with Australia as another extended deterrence ally in the Indo-Pacific."
However, if this is about pursuing a retrenchment foreign policy — if that’s what “America First” means — which I believe is an unseen battle within the administration, then allies have limited options. As an extended deterrence ally, you can only be so persuasive because ultimately, you need a United States willing to engage with allies, be transparent, and fulfill the software element of extended deterrence. Being credible on the software side seems contradictory to a retrenchment strategy.
Allies need to determine whether this is about recalibrating burden-sharing in the new political climate or if the United States is reducing its international commitments. The second scenario is much more challenging and drives allies to consider hedging strategies.
Jordan Schneider: It’s complicated because the answer is both. Pranay pointed out that some people believe one thing and others believe something else. We have a president who frequently changes his mind. So what’s the appropriate response?
Junichi Fukuda: Regarding the hardware issue, I’m not overly concerned about the modernization of US strategic nuclear forces. The United States is modernizing its strategic nuclear weapons, and there’s an option for uploading nuclear warheads on existing platforms.
My concern lies more with the future trajectory of developing theater nuclear forces, such as sea-launched cruise missiles from submarines. These types of theater nuclear weapons would be essential for Japan’s defense in the future. Given the current administration’s position on cutting the defense budget, I question whether such new nuclear capabilities will ultimately be realized.
On the software issue — the political relationship between the United States and Japan — there are several possibilities. First, there’s conflict in the trade area. The United States has increased tariffs on Japan, and we’re currently negotiating this matter. Japanese people might find it difficult to rely on the United States for security while we’re engaged in economic disputes.
Simultaneously, the Trump administration is attempting to address the challenge posed by China. Most security experts in the administration appear to be “prioritizers” — they would withdraw from the European theater but concentrate on strengthening capabilities in the Pacific to counter China’s threat. This approach provides some reassurance to us.
The situation remains difficult to analyze fully at present. Overall, we remain confident in continuing the alliance relationship for now, though the future is somewhat unpredictable.
Jordan Schneider: It’s interesting, Junichi, because you’ve seen this incredible earthquake in European politics triggered by just a handful of speeches. It seems to me that only people like you are paying close attention, not necessarily the entire Japanese or South Korean political establishments. Am I wrong? Do you think it would take something as explicit as a J.D. Vance or Pete Hegseth speech saying, “We don’t care about you guys,” to trigger the same kind of awakening that seems to have happened in Poland and Germany?
Junichi Fukuda: That’s a nightmare scenario we hope to avoid. Currently, there appears to be conflict within the administration. One faction focuses on confronting China, recognizing the necessity of maintaining US hegemony in the Indo-Pacific region. The other faction consists of isolationists who advocate withdrawing US forces from every theater worldwide, preferring to concentrate resources on domestic politics. The future direction of the current administration remains uncertain, with potential internal struggles ahead.
Jordan Schneider: The very existence of this debate is unprecedented from a post-1945 perspective. Perhaps now is a good time to discuss the politics of nuclear armament in both South Korea and Japan. If we remain in this awkward, subterranean debate — or move toward the more alarming scenario of J.D. Vance expressing indifference toward Japan — how might this affect Japan and South Korea’s nuclear postures?
Junichi Fukuda: Japan’s nuclearization has traditionally been an unthinkable issue, not widely discussed. However, as someone studying nuclear deterrence, I’ve had many opportunities to address this topic. Last month, I attended a conference where American experts frequently discussed the possibility of Japan nuclearizing in the future.
The primary condition under which Japan might consider nuclearization would be a lack of confidence in the credibility of US extended deterrence. A secondary scenario would involve South Korea pursuing nuclearization first, which might prompt Japan to follow suit. The specific circumstances that would trigger such scenarios remain unclear to me.
Pranay Vaddi: From a US perspective, it’s difficult to imagine any scenario where the United States benefits from ally proliferation. We’ve seen comments by the Vice President questioning whether stationing US nuclear weapons in Poland makes sense — indicating that proliferation of US weapons to other allies isn’t necessarily on the table. This struck me as an off-the-cuff reaction rather than the product of an interagency process.
The challenge for the Trump administration is reconciling several objectives — preserving the status quo regarding the number of nuclear-armed countries, upholding the Nuclear Non-Proliferation Treaty, and renegotiating burden-sharing agreements or pursuing retrenchment. These goals conflict with each other.
Japan is a technologically advanced nuclear country with nuclear technology and reprocessing capability. They’ve committed to neither possessing, producing, nor introducing nuclear weapons into their territory as part of their peace constitution. They remain an importantUS partner in nuclear energy, extended nuclear deterrence, and nuclear disarmament. Japan uniquely embodies all the contradictions of nuclear policy in one bilateral relationship.
Countries like Japan, South Korea, or Poland cannot simply decide to acquire nuclear weapons overnight. The process requires specialized facilities, legal and regulatory changes, withdrawal from the NPT, and consideration of potential US export controls and sanctions. This timeline gives adversaries opportunity to react — not just economically. If North Korea observed South Korea pursuing nuclear weapons while US extended deterrence guarantees appeared shaky, they might preemptively strike those facilities or initiate conflict. The risk of conflict increases when an ally with weakened US security guarantees pursues nuclear capabilities — an important consideration for countries weighing this decision.
Vipin Narang: Those who identify as “America first” — which includes all of us, as I reject the notion that only the Trump administration puts America first while the Biden administration didn’t — should oppose allies acquiring nuclear weapons for at least three reasons.
First, we have historically opposed allied proliferation in Washington because we wanted to minimize the number of independent decision centers for initial employment or escalation decisions. This is a sanitized way of saying we didn’t want France starting a nuclear war we’d have to finish. The French — whom I genuinely respect — had a strategy where their independent nuclear capability would be employed when the French President determined vital interests were at stake. However, they couldn’t finish such a conflict, leaving the US to manage the aftermath against the Soviet arsenal. This thinking persists today when discussing the credibility of European deterrence. France can initiate a conflict, but cannot conclude it.

Similarly, other allied nuclear powers could never develop damage limitation capabilities comparable to the United States independently. An allied proliferator would acquire nuclear capabilities that could initiate a nuclear war and chain-gang the US into it — precisely what the US has always sought to avoid.
Second, while Kenneth Waltz famously argued “more may be better” from a retrenchment perspective, the risk of accidents increases substantially. Smaller states with limited arsenals facing more capable nuclear adversaries with head starts might develop itchy trigger fingers or lack the institutional infrastructure to effectively manage these weapons. The accumulated risk of accidents grows with each additional nuclear-armed state.
Third, as Pranay and Fukuda-san mentioned, the threat to the NPT is real, as is the potential cascade effect if one ally — particularly South Korea, given the growing political consensus there for at least developing a hedging capability — acquires nuclear weapons. I doubt the NPT could survive a democratic state in good standing withdrawing to pursue nuclear weapons. Japan might follow, along with Poland, Ukraine, Germany, Saudi Arabia, Turkey, and a number of other countries if the floodgates opened.
Pranay’s point is important: these countries would pursue nuclear weapons in an environment where their adversaries have both a vote and a head start. Historically, no state has acquired a credible nuclear weapons capability in less than five years from the decision point, and a survivable arsenal typically requires a decade or more.
Regarding probabilities — there’s a zero percent chance an ally proliferates by the end of 2025? The timeline doesn’t work. By 2030? I’d wager the odds are more than 50 percent, though as an academic I don’t have much money to bet — that at least one ally will have a credible latent nuclear capability by 2030-2035 if current trends persist.
Jordan Schneider: Just wait until you get all those Polish and Saudi contracts to help write their nuclear doctrine.
Vipin Narang: You can reach Pranay, my agent, at prvaddi@mit.edu.
Jordan Schneider: Let’s talk about France. They were exceptionally difficult throughout the Cold War, no?
Vipin Narang: I love them, but one France is enough.
Jordan Schneider: This is precisely the point about “America First.” Nuclear weapons are incredibly powerful — they provide tremendous leverage, allowing you to dictate terms to other countries, constrain their actions, and influence whether they initiate conflicts.
Consider how the US effectively prohibited Chiang Kai-shek from invading mainland China in 1962 because he lacked nuclear weapons. Our ability to maintain global stability and, as Vipin mentioned, prevent conflicts that we would ultimately have to resolve actually enhances American security. The alternative makes the world a lot more dangerous.
The notion that Putin would remain passive for five years while Poland develops nuclear weapons is unrealistic. We’ve already witnessed this scenario play out with Israel, Syria, and Iran. Russia would undoubtedly take action. Imagine the consequences of a Polish nuclear facility being bombed by Russian aircraft — the global ramifications would be catastrophic.
Vipin Narang: Poland remains a NATO member, so that scenario involves Article 5 and risks war with Russia over a counter-proliferation strike. These are low-probability events.
Pranay Vaddi: Attempts at retrenchment could actually accelerate the path to great power confrontation that you’re trying to avoid. Regarding our discussions with French colleagues — you don’t necessarily need to implement extended deterrence exactly as the United States has done. We’ve pursued an expensive strategy heavily reliant on nuclear capabilities that requires an enormous defense budget.
Perhaps in their Euro-deterrent approach, the French don’t need 3,800 nuclear warheads or a triad similar to ours. They might achieve more with conventional forces and missile defense systems. However, they ultimately need an approach that accomplishes the same objectives: reassuring eastern flank allies on Russia’s borders that you could meaningfully engage in conflict and either deter or defeat Russian aggression against those allies.
This is extraordinarily challenging. The United States has invested over seven decades in continuously refining this approach. The work on extended deterrence is never complete. As Fukuda-san knows well, the meetings between the United States and Japan throughout the year on extended deterrence are extensive, regularly scheduled, and ongoing. It requires dedicated staffing and expertise on both sides. This isn’t something another country can simply adopt if the United States withdraws those commitments.
Jordan Schneider: What frustrates me about much of the MAGA-influenced foreign policy is its simplistic thinking — reminiscent of middle school debate logic.
There are reasons why the world exists in its current state. I thought conservatives valued the principle of Chesterton’s Fence — not dismantling established systems without understanding their purpose. The transition to a new world order could be dangerous and catastrophic.
Spending an extra $500 billion annually to prevent 20 countries from acquiring nuclear weapons actually represents an excellent deal.
Vipin Narang: It is indeed an excellent deal.
Jordan Schneider: A historically unprecedented deal. You would have accepted this arrangement 100 times out of 100 if you were present at Alamogordo in 1945.
Vipin Narang: This represents a bipartisan consensus. Republican or Democrat — Pranay and I often find ourselves aligned with traditional Republican views on strategic deterrence and extended deterrence, sometimes surprising ourselves with how much common ground we share. Those traditional voices are being marginalized, if not completely excluded, from the Trump administration.
This represents a different approach than anything we’ve seen in the post-World War II era. There was bipartisan consensus that we were committed to extended deterrence, with debates focusing on implementation methods rather than questioning the fundamental commitment itself. That’s why this moment seems distinctive.
To be fair, I don’t know where the Trump administration will ultimately land on this issue, as Fukuda-san and Pranay both noted — there are various competing voices within it.
Vipin Narang: At the core of extended deterrence credibility lies predictability and consistency. The very existence of this debate creates problems for the credibility of extended deterrence.
Jordan Schneider: Junichi, how are you feeling about all this?
Junichi Fukuda: At the administration level, I cannot predict the future because President Trump is unpredictable. However, at the congressional level, there exists concrete bipartisan agreement. The United States must continue extended deterrence toward its allies. Two years ago, a congressional report from the Bipartisan Commission — the Strategic Posture Report — emphasized continuing and even increasing the credibility of extended deterrence. At the congressional level, bipartisan agreement will persist in the future. Administrations last just four years, but Congress continues.
Jordan Schneider: I appreciate your optimism. I’m curious, Junichi — when you first entered this field and began studying nuclear extended deterrence and nuclear policy, what were the most extreme scenarios being discussed? How much more extreme is our conversation over the past 45 minutes compared to anything you’ve encountered before?
Junichi Fukuda: I began studying international relations in the late 1990s. At that time, the most severe concerns involved bioterrorism around 1997 or large regional civil wars. Nuclear war between great powers was definitely not considered a possibility. Now we’re discussing nuclear war. The situation has changed dramatically, forcing us to contemplate the unthinkable.
Pranay Vaddi: For the past 30 years, nuclear policy as a subject area was limited to specialists and experts. Now this debate about extended deterrence reminds us how deeply connected US nuclear strategy is to other elements of US grand strategy and foreign policy goals.
After the Trinity test, as nuclear strategy developed, it became integral to American grand strategy for confronting and containing communism, rebuilding decimated countries including close allies and former adversaries like Germany and Japan. This created a remarkable market for American goods and innovation through the Marshall Plan and other foreign aid efforts.
If you disconnect extended nuclear deterrence from foreign policy and our economic strategy, you can have simplistic conversations about whether we should continue extended deterrence or maintain forward-based troops. The reality is these elements have been interconnected for over 70 years.
Vipin and I have written about how much effort the United States put into rebuilding the world in the 1950s and 60s, ensuring that the United Nations, economic integration, and globalism — which nationalist trends in every democracy now resist — would help prevent another world war. Now the administration is attempting to remove the economic pillar while simultaneously questioning sacred principles of extended nuclear deterrence.
Our assumption when we wrote about this in January was that the economic benefits to the United States would eventually lead back to a coherent extended nuclear deterrence strategy. However, when economic interdependence and the accompanying political relationships diminish, I might question the American commitment to extended nuclear deterrence if we become less reliant on international trade due to efforts to retrench and reshore everything from industry to military capabilities.
These elements are all connected. Retrenchment, if implemented comprehensively, can severely damage US national security.
Deterrence with Chinese Characteristics 玉石俱焚
Jordan Schneider: We’ve progressed quite far into this discussion without mentioning China’s efforts to update its nuclear arsenal. This factor seems irrelevant in the Trump calculation, but it’s worth discussing how countries in Asia perceive this development. Junichi, could you provide a brief overview of what has happened in China over the past decade, and what this modernization means for countries in the region as they evaluate their strategic environment?
Junichi Fukuda: Historically, China’s nuclear assets were limited to approximately 200 nuclear weapons. At that time, analysts described China’s nuclear strategy as “minimum deterrence” — though this is a Western concept that might not align with China’s actual thinking.
China has gradually changed its approach to nuclear weapons. Recently, China has rapidly increased its nuclear arsenal, adding approximately 100 nuclear warheads annually. In the long term, China’s strategic nuclear arsenal may reach 1,500 warheads, potentially achieving parity with the United States and Russia.
The purpose behind this expansion remains unclear, but several possibilities exist. One apparent reason is to gain national prestige and achieve the same international status as Russia and the United States by creating parity with them.
Another potential reason involves creating a strategic stability-instability paradox in the Taiwan Strait contingency. By increasing its strategic nuclear arsenal, China might deter United States intervention against Chinese aggression toward Taiwan.
Their final objective, however, remains unknown. China has stated that by 2029, they intend to build a “world-class military,” which likely means achieving the same scale as the United States. This suggests their nuclear forces will eventually match the current US strategic nuclear arsenal.

Jordan Schneider: A question from Japan’s perspective — does the difference between 200 versus 1500 nuclear weapons actually matter?
Junichi Fukuda: Currently, it doesn’t matter as much, but we’re concerned about what would happen in the next decade. Our nuclear concern is focused on the medium to long term, particularly around 2030-2035.
Jordan Schneider: Why? How do more nuclear weapons with better delivery capabilities matter strategically?
Junichi Fukuda: If China possesses 1000 or 1500 nuclear weapons, they might be able to deter the United States from intervening in a Taiwan Strait contingency, creating a decoupling and instability paradox. This would be a major concern for us. In the short term, we’re more concerned about China’s increasing conventional capabilities, which are changing local military balances and might enable China’s invasion of Taiwan by 2027. But regarding nuclear issues, our concerns focus on the 2030-2035 timeframe and beyond.
Vipin Narang: China’s expansion is real and occurring faster than we anticipated. It’s designed to challenge the United States’ force sizing principles. While we don’t fully understand their motivations, we must prepare for the possibility that China is developing a nuclear posture and strategy to provide cover for regional aggression and coercion against US interests and allies.
We took this very seriously in the Biden administration. For context, we have these formal documents like the Nuclear Posture Review, which is unclassified and available to everyone. Following this parent document is the Presidential Nuclear Weapons Employment Guidance, which I worked on with Pranay. There’s an unclassified report to Congress known as the “491 Report” that I would recommend reading closely.
When the previous employment guidance was issued during the Trump administration around 2019, China was just emerging as a nuclear concern. There was recognition that China would challenge the US force posture, but the specific nature of that challenge wasn’t yet clear. The current document represents an evolution, with continuity between the Trump and Biden administrations’ guidance. However, it takes seriously, for the first time, the prospect of multiple peer strategic challenges, where China can no longer be treated as a “lesser included case.”
An important point that’s often overlooked is that it’s not just about the numbers. China will reach approximately 1,000 nuclear weapons by 2030 and potentially 1,500 by 2035, which represents quantitative parity with New START treaty levels. What’s more concerning is the composition of their force development.
If China had remained consistent with its long-standing assured retaliation strategy and focused solely on a sea-based force similar to the UK, we wouldn’t need to adjust our nuclear force posture. Instead, they’re developing hundreds of hardened silos in remote areas, perfectly spaced, which serve as nothing other than counterforce targets for the United States. Given our strategy to limit damage to the US homeland and our allies, China knows we must target and hold those forces at risk.
Under New START, we only have 400 ICBMs with single warheads and a limited number of SLBMs (Submarine-Launched Ballistic Missiles) at sea at any given time. Hundreds of Chinese ICBMs in remote regions would consume a large portion of our strategic forces and could make us vulnerable against Russia. We’re observing collusion and coordination between Russia and China. If we’re engaged in conflict with Russia and have expended some nuclear forces to maintain strategic deterrence because of their actions in Ukraine, China might see an opportunity to act because we no longer have sufficient forces to maintain strategic deterrence against them.
Their force structure appears carefully and intelligently designed to undermine our capabilities and sizing principles. We recognized the need to respond in ways that enable us to maintain both strategic and regional deterrence in a multiple-peer world across multiple theaters, especially given the coordination between Russia and China — and we shouldn’t underestimate North Korea either.
We conducted a year-long process to assess adjustments to the US force posture for strategic and regional deterrence in this new reality. As Fukuda-san mentioned, we’re implementing changes because Congress mandated it, but these changes also offer deterrence advantages. The security environment continues to deteriorate, and we can no longer deny the value of having a purpose-built maritime regional deterrence capability that frees up strategic platforms for strategic deterrence.
This challenge demands our attention. I’m concerned about the administration potentially rushing to reach a deal with Russia on arms control to extend New START without considering the implications for China. During the first Trump administration, Marshall Billingsley actually attempted to coordinate arms control strategies. I’ll defer to Pranay on this since he knows more about it than I do. But that approach is crucial — these issues must be coordinated within our own strategy. We need to consider what we’re willing to accept with Russia while keeping China in mind, and vice versa.
Pranay Vaddi: I’ll just highlight one additional point. Beyond everything that Vipin and Fukuda-san have raised regarding China’s changing posture — the warhead buildup, the decision to place nuclear weapons in silo ICBMs (which are vulnerable to nuclear strikes and therefore need to launch quickly in a nuclear war scenario), and their approach to survivability that the US would have to contend with — the Chinese are also modernizing cyber capabilities, counterspace technologies, and conventional precision strike systems. These capabilities could be categorized as counter-intervention measures since the US is also arming itself for a potential conflict in the Indo-Pacific. Alternatively, they could be used aggressively as part of a strategy to coerce under the nuclear umbrella.
The reality is that much of this will depend on one person’s decision-making and whether China decides to maintain or change its historic nuclear doctrine established since Mao’s time — characterized by restraint, minimum deterrence, and a no-first-use policy. If any aspects of this doctrine are changing, we probably wouldn’t be the first to know, as we’ve been unable to sustain diplomatic dialogue with China on strategic stability and nuclear policy issues for the past decade or two.
The Biden administration held just one consultation with Chinese colleagues on this particular topic. As with many other national security issues in the US-China relationship, China’s willingness to discuss nuclear matters depends on the political climate between our countries. If conditions seem favorable for US-China discussions across various topics, they might engage on nuclear issues as well. However, if relations are unfavorable — as they have been for several years due to incidents involving surveillance balloons, Nancy Pelosi’s visit to Taiwan, or tensions during the Trump administration — they won’t discuss these matters with us.
This creates a fundamental problem — how are US policymakers supposed to understand the nuances of China’s policy regarding its modernizing nuclear posture if we can’t meet for discussions? Setting aside any attempts at arms control agreements or diplomatic efforts to limit China’s buildup, progress is impossible unless both sides can engage in dialogue. Despite having one meeting during the Biden administration, all our attempts to encourage, incentivize, or facilitate a second meeting were unsuccessful.
There have been some positive developments. Before leaving office, Presidents Biden and Xi established a joint understanding regarding the use of artificial intelligence in nuclear employment decisions, essentially agreeing that humans should remain in the loop for any nuclear deployment or termination decisions made at the presidential level. Additionally, the two countries now exchange notifications before intercontinental ballistic missile tests. While these are small confidence-building measures, they don’t address the central issue — China is the only nuclear weapons state under the Non-Proliferation Treaty that is quintupling its arsenal.
The United States and China must discuss this issue, or else, in worst-case scenario planning conducted by the Pentagon, we’ll have to assume that China intends to build an arsenal qualitatively equivalent to that of the United States — one designed to undermine US nuclear strategy, as Vipin mentioned. This would force the US to respond with its own buildup, creating a world that benefits no one.
Jordan Schneider: Junichi, you’ve been the most positive and sanguine out of all four of us throughout this conversation. Would you like to conclude on a high note? What are you looking forward to over the next few years?
Junichi Fukuda: Actually, I’m not particularly optimistic. Having nuclear weapons in Japan is politically and economically challenging, with very high barriers. We simply don’t want to consider this option, which is why we’re always concerned about strengthening the credibility of extended deterrence and maintaining our alliance relationship.
The future is unpredictable, especially under the Trump administration, so we must consider various scenarios. However, nuclear weapons are not the most desirable path for Japan. The least desirable option would be to bandwagon with China, which we must avoid at all costs. If we face a truly existential situation where we lose confidence inUS extended deterrence, we might decide to pursue nuclear weapons despite the damage this would cause to the Non-Proliferation Treaty. But this is certainly not our preferred outcome.
Jordan Schneider: Why are you so confident that nuclear weapons would be the preferred path versus an accommodation with China?
Junichi Fukuda: Bandwagoning with China would require compromising Japanese sovereignty. Looking at Japan’s long history with China, there is no precedent for such a decision. Japan has at least 1,500 years of recorded history, and during that time, our country was occupied by a foreign power only once — from 1945 to 1952 by the United States. We have never experienced Chinese occupation of our land.
This represents a fundamental difference between South Korea and Japan. South Korea has a long history of being part of China’s tributary system, but Japan has no such experience. We cannot align with China under any circumstances.
To avoid that scenario, we might need to consider independent nuclearization if we lose confidence in the alliance.
Jordan Schneider: Vipin, Pranay — we can’t end on that note.
Vipin Narang: Let me try to be more optimistic. There’s considerable uncertainty right now. We transitioned from an administration that was very careful with its words to avoid sending mixed signals or giving the impression of internal divisions. For the most part, we spoke with one voice and maintained discipline on these issues.
The Trump administration has a different style. The president speaks frequently, and his statements aren’t always consistent. He doesn’t like nuclear weapons, but if that’s true, he should appreciate extended deterrence — though that connection isn’t always obvious. There’s certainly a battle within the Trump administration over the direction of foreign policy and grand strategy, as Pranay mentioned.
We should take a moment and wait to see which direction this goes. The sky isn’t yet falling on extended deterrence or NATO. The NATO ambassador was very clear about the US commitment to NATO. It would be prudent for allies — and this was true during the Biden administration as well — to contribute more, which they have done. The burden-sharing issue is real, bipartisan, and consistent. This focus isn’t necessarily bad for American security, regardless of which administration is in office.
However, there’s a possibility that things could move in a different direction. It’s important for allies to consider what a world without American leadership in the alliances might look like, while also recognizing that the bipartisan continuity we’ve seen on these issues might prevail in practice. It’s still early — only 90 to 100 days have passed — so I remain in wait-and-see mode. I continue to hope for the best, but it isn’t imprudent to prepare for a very different world.
Pranay Vaddi: This issue is central to US national security. The more people outside the nuclear space learn about extended nuclear deterrence — its history, our current strategy, what we’ve done and why — from people like Vipin who’ve held important positions at the Pentagon or from allies who have experienced being recipients of extended nuclear deterrence, the better.
Every time I see foreign policy generalists learn about extended nuclear deterrence, a light bulb seems to go on. They understand that this is fundamental to what the United States has built in the world, benefiting the average American. I’m somewhat optimistic that as more people become aware of these issues and critically examine foreign policy decisions that might undermine extended nuclear deterrence, they’ll speak out in support of not just maintaining the status quo but improving our approach.
I want to thank you, Jordan, for having us on. Podcasts, articles, news coverage — all of these help people understand why we approach extended nuclear deterrence the way we do and recognize that having more states with nuclear weapons is inherently detrimental to the United States. I believe people in the current administration instinctively understand this as well. The key will be connecting these dots to help them conclude why specific actions in extended nuclear deterrence are necessary. That’s the source of my optimism.
Jordan Schneider: Let’s close with some reading recommendations. How about two from each of you? Jun, would you like to start with two books?
Vipin Narang: I’d like to recommend Under the Nuclear Shadow by one of my former students, Fiona Cunningham, which just came out.
Jordan Schneider: You can’t recommend that one! We already did a show with her.
Vipin Narang: I highly recommend it. My second recommendation is the updated version of Managing Nuclear Operations. This is quite technical. While Fiona’s book is high-level and accessible for anyone interested in China, Managing Nuclear Operations is on the detailed end of the spectrum. Charlie Glaser, Austin Long, and Brian Radzinsky re-edited this classic with updated chapters from experts like Franklin Miller and James Miller. It provides an excellent introduction to how US nuclear strategy and policy are developed. If you’re interested in that topic, I highly recommend it — it’s a very good update to the classic 1987 volume edited by Ash Carter, Steinbrenner, and a third co-editor whose name escapes me.
Jordan Schneider: Are we telling people not to read Annie Jacobson’s Nuclear War?
Pranay Vaddi: I haven’t read it, so I can’t speak to whether it should be recommended or not.
Jordan Schneider: You guys are so diplomatic. I’ll say it directly — don’t read it. It reads like a journalist who doesn’t really know what they’re talking about. I caught one or two historical errors just from my limited knowledge. It gave me the impression of someone with too much of an agenda to be careful with their sources.
Vipin Narang: I appreciate the original sources. I recently taught my class on extended deterrence and discovered an obscure article by James Schlesinger from 1962 explaining why we extend deterrence to Western Europe and NATO. Remarkably, the arguments haven’t changed between 1962 and 2025. It’s a RAND chapter that’s quite difficult to find. I was stunned when I read it carefully, realizing how much we’re simply reinventing the wheel. [Link here!]
I’m very humble about the fact that scholars like Schelling, Brody, Schlesinger, Earl Ravenhall — all published in International Security — along with Ash Carter, Frank Miller, and others who preceded us, had already thought through all these issues. We’ve forgotten many of their insights because we had a 35-year interregnum when we didn’t have to consider the importance of extended deterrence and nuclear deterrence more broadly. For the audience, I recommend going back to the original texts — you’ll be surprised how little has changed.
Jordan Schneider: Pranay, Junichi — any recommendations come to mind?
Pranay Vaddi: I have two recommendations. First is a report by the American Academy of Arts and Sciences authored by Tong Zhao and Dmitry Stefanovich. They write from Chinese and Russian perspectives about why those countries are concerned about US missile defense and its implications for strategic relationships. For those of us who focus on arms control policy and try to understand how the administration might approach hypothetical denuclearization talks with Russia and China, this is essential reading. Both authors are colleagues who have studied this area extensively. It’s not a book, so you can gain valuable insights from two genuine experts in just 50-60 pages.
The second recommendation is an older book from the late 1980s by Richard Betts called Nuclear Blackmail and Nuclear Balance. I found it particularly interesting as the Ukraine conflict progressed while I was still at the NSC. It reminds nuclear policy experts that nuclear weapons aren’t magical solutions. Attempts to use them in world crises — either to force adversaries to back down or to coerce for other military objectives, as in the Vietnam War — have produced mixed results at best. Understanding this history is important for our current era, where we’ve seen Russia issue almost daily nuclear threats in the context of a conventional war it initiated. Those are my two recommendations.
Junichi Fukuda: I’ve chosen two books. The first is another classic, Glenn Snyder’s Deterrence and Defense: Toward a Theory of National Security. This book is quite important because it addresses the problem of the stability-instability paradox, which directly applies to the current situation in the Pacific. If you want to study the stability-instability paradox, I recommend reading Graham Allison’s work on deterrence and defense.
The second recommendation is Brad Roberts’ The Case for US Nuclear Weapons in the 21st Century from 2015. This book is widely read in Japan as it directly discusses options for strengthening extended deterrence for allies in the Indo-Pacific. Many Japanese experts interested in this subject have read this book, so if you read it, you’ll have common ground for discussions with those experts in Japan. I highly recommend it.