JIIA Strategic Comments (2025-16)The Perils of “Selective Proliferation” for U.S. Allies and the Global Order

Papers in the "JIIA Strategic Commentary Series" are prepared mainly by JIIA research fellows to provide comments and policy-oriented analyses of significant international affairs issues in a readily comprehensible and timely manner.

The Perils of “Selective Proliferation” for U.S. Allies and the Global Order

In their article titled “America’s Allies Should Go Nuclear” (Foreign Affairs, November 19, 2025)¹ , Moritz Graefrath and Mark Raymond make the case for selective proliferation, arguing that allowing U.S. allies such as Canada, Germany, and Japan to acquire nuclear weapons would both enhance their security and bolster the international rules-based order in front of the Chinese and Russian threats and revisionist actions. 
This article challenges these assertions, contending that such a strategy is fundamentally misguided and would, in practice, produce the exact opposite—undermining the security of U.S. allies and the United States itself, as well as inflicting irreversible damage on the non-proliferation regime and the post-1945 international order. 
Rather than pursuing selective proliferation, the development of advanced conventional capabilities by allies, the use of allied conventional means to support U.S. nuclear operations, and enhanced cross-regional deterrence cooperation are identified as the most immediate and feasible ways to strengthen deterrence.

Selective Proliferation Would Endanger the Security of U.S. Allies and the United States Itself

The first claim advanced by the article is that nuclear proliferation by Canada, Germany, and Japan would provide “the most dependable protection against the threats of regional foes.” In this view, a Japanese nuclear arsenal would allegedly ensure that the country “does not fall under Chinese control”, while a German nuclear capability would enable Europe “to provide for its own security today.”
The central problem with this argument is that it is both exceedingly narrow and conceptually vague. It treats nuclear weapons as the ultimate Wunderwaffe, whose mere acquisition would automatically strengthen a state’s security, irrespective of its specific strategic environment. At no point does the article engage with what effective deterrence actually requires. Nuclear deterrence does not arise from the simple possession of a given number of warheads; it depends on a sustained process of technical development, force-posture construction, and doctrinal formulation that far exceed the basic ability to build nuclear devices. Hardware and software are inseparable in this domain, shaping the three cardinal Cs of deterrence: capabilities, credibility, and communication.
Regarding capabilities, the authors’ argument is weakened by their vagueness about what “selective proliferation” would concretely entail. Referring simply to “nuclear weapons” avoids engagement with essential technical and operational requirements. Would Germany, for example, need to develop a full-fledged nuclear triad? How many warheads should Canada be expected to produce? Would Japan be able to conduct nuclear testing in its vicinity, or would the United States be willing to cooperate to the extent of providing relevant warhead data for simulation? Answering such questions would be absolutely necessary to ensure the reliability of a developing nuclear arsenal. 
Moreover, none of these states currently possesses the Intelligence, Surveillance, and Reconnaissance (ISR) infrastructure required to guarantee credible delivery systems. If they were to rely on the United States for such enablers—as they do today—the autonomy that the authors associate with nuclear acquisition would be significantly diminished. By leaving these fundamental questions unaddressed, the authors substantially undermine their own argument.
Furthermore, the authors’ concept of “selective proliferation” is ahistorical and seemingly detached from temporal reality, as if such a process could be accomplished overnight. The fact that Canada, Germany, and Japan possess advanced technological capacities in no way implies that they could develop reliable nuclear weapons within a matter of weeks. The production of weapons-grade fissile material, its conversion into metallic form, the fabrication of appropriate detonation systems and firing circuits, the miniaturization of a dependable warhead, its integration with suitable launchers, the testing of both the warhead and delivery mechanisms, and the construction of safe and secure infrastructure to house these capabilities—all of these concrete technical steps would require months or, more plausibly, years to complete. Potential economic sanctions would likely make that process even longer and more difficult.
It is precisely because the authors overlook these technical requirements that their assertion—that proliferation would enhance the security of these states—is fundamentally flawed. The extended timeframe required for nuclear development would inevitably create a significant window of vulnerability marked by two challenges.
First, it would risk exposing these states to potential counter-proliferation measures by their adversaries. Can it reasonably be assumed that China, North Korea, or even Russia would remain passive if Japan were to pursue nuclear weapons? 
Despite Japan’s precarious security environment, nothing in the current circumstances would justify withdrawal from the NPT under Article X, which permits such action only if “extraordinary events, related to the subject matter of this Treaty, have jeopardized the supreme interests” of the state. In such a scenario, Japan would be perceived as a rogue proliferator, and, following the Iranian precedent, its adversaries might consider preventive conventional strikes against Japan a legitimate counter-proliferation measure.
Given that the legitimacy of Japan’s nuclear acquisition would be vigorously contested in both international and domestic arenas, the United States would face diminished incentives to maintain its extended deterrence commitments. Consequently, pursuing nuclear proliferation would likely degrade rather than enhance Japan’s national security. 
Moreover, it would directly affect the United States: any counter-proliferation action targeting Japan would endanger U.S. forces and interests in the region. Far from alleviating the U.S. security burden, as the authors suggest, it would compel the United States to confront difficult decisions regarding the nature of its response, with potential ripple effects for the other U.S. extended deterrence frameworks. 
The second challenge, beyond the security threats Japan faces, would be the establishment of a stable and credible deterrence framework over the long term. The notion that the mere acquisition of nuclear weapons would produce an effective deterrent effect per se amounts to little more than magical thinking. 
Why do states such as France and the United States continually modernize their nuclear forces and periodically revise their nuclear doctrines? Among other reasons, because they recognize that deterrence requirements are shaped by evolving security environments, and that nuclear weapons alone are insufficient. They must be embedded within a carefully designed—and regularly updated—strategic framework tailored to the threats perceived as endangering vital national interests. 
On this basis, an independent Japanese nuclear deterrent would not resolve the challenge of building a credible and reliable nuclear deterrence architecture for many years, thereby significantly limiting the effectiveness of developing a nuclear arsenal, while also increasing the risk of counter-proliferation measures.
Compounding these misconceptions is the bias evident in the authors’ argument, which fundamentally overlooks the agency and long-standing strategic analysis of the three countries regarding nuclear weapons. While the authors correctly acknowledge the obstacle posed by Japanese public opposition to proliferation—thereby illustrating the importance of taking into account domestic political costs—they fail to consider the historical record showing that successive Japanese governments have consistently rejected nuclear weapons based on a pragmatic, strategically informed assessment of the consequences such a decision would entail.
Various internal studies were conducted within the Ministry of Foreign Affairs and the Defense Agency (now the Ministry of Defense) in 1968, 1970, and 1995 regarding the possibility of Japanese nuclear proliferation. All of these studies concluded that pursuing nuclear weapons would likely reduce, rather than enhance, Japan’s security. They identified multiple risks: triggering an arms race with nuclear-armed neighbors, providing adversaries with incentives for preventive strikes, undermining the non-proliferation regime, potentially isolating Japan internationally and straining its relationship with the United States, imposing substantial economic costs, exposing Japan to potential sanctions, and facing the practical challenge of lacking suitable territory for nuclear testing.²  
Taken together, these factors led to the rational decision to forgo the development of a national nuclear program, instead relying on U.S. extended deterrence and seeking to strengthen the alliance—a strategy that has become the cornerstone of Japan’s deterrence and defense policy. While historical background does not constitute evidence for assessing the likelihood of proliferation in response to a changing international environment—policy shifts are always possible—it nonetheless underscores the value these actors have consistently attached to extended nuclear deterrence as a strategic choice. As long as they continue to reaffirm their commitment to this security model, the political decision to pursue nuclear weapons will remain unlikely. In Japan’s case, this commitment was reaffirmed as recently as February during the Ishiba-Trump meeting³  and again in October during the Takaichi-Trump meeting.⁴  

The Selective Destruction of the Rules-Based Order

The authors contend that “selective proliferation”, by rebalancing military capabilities in favor of states opposed to revisionist powers, “would help prevent further erosion of the rules, norms, and institutions of the post-1945 order, including the norm against conquest.” This claim is highly debatable and, in effect, valorizes the very dynamics it purports to condemn. 
To begin with, any discussion of the rules-based order must acknowledge the central role of the non-proliferation norm, which constitutes one of its foundational pillars. The Nuclear Non-Proliferation Treaty (NPT)—one of the most universal international agreements, with 191 states parties—has contributed to the maintenance of international security for more than five decades. The non-proliferation norm is thus deeply intertwined with the broader balance of power and, as the precondition for access to the peaceful uses of nuclear energy, has been internalized by an overwhelming majority of states.
Moreover, the strength and influence of a norm depend significantly on which states adhere to it. A norm is reinforced when it is upheld by a set of “critical states”, particularly those that the norm is designed to constrain.⁵  In the case of nuclear non-proliferation, Japan and Germany were among the principal states whose proliferation the United States and the Soviet Union sought to prevent, and they were central considerations in the negotiations leading to the NPT in the late 1960s. If these two critical states—often regarded as “model students” of the NPT—were to defect, their development of nuclear weapons would not simply weaken the non-proliferation norm but effectively bring it to an end. It would mark the demise of the NPT by signaling the ascendancy of double standards rooted in alliance politics and geopolitical alignment over universal norms and treaty compliance.
If the international rules-based order is to retain credibility, it cannot be treated as an à la carte system. The NPT is already subject to increasing criticism from many non–nuclear-weapon states, which denounce its inherent inequalities and the perceived lack of disarmament progress by the five nuclear-weapon states. Endorsing selective proliferation would only intensify this frustration and reinforce the view that the NPT is no longer viable or deserving of support.
U.S. adversaries would be the first to denounce such blatant inequality—likely with strong backing from non-aligned states. Following initial condemnation, these adversaries would be incentivized to respond in kind; under such circumstances, the prospect of China and Russia offering explicit, open support for Iran’s nuclear program—or that of other states—would become entirely plausible, while the risk of existing export-control regimes becoming dysfunctional would rise substantially. 
Moreover, beyond adversaries, other U.S. allies could also be incentivized to follow suit. The authors’ claim that South Korea, for instance, lacks incentives to acquire nuclear weapons in the event of Japanese proliferation is unconvincing. From the standpoint of both security rationality and East Asia’s regional political dynamics, nuclear acquisition by one of these states would generate powerful incentives for the other. South Korean domestic political pressures, historical sensitivities, and strategic concerns regarding regional stability and its own security would likely intensify calls for a corresponding nuclear capability.
These ripple effects call into question the very premise of “selective” proliferation. The term presupposes that the United States retains the ability to choose which states acquire nuclear weapons, to prevent others from doing so, and to reap security benefits from this process. Yet if key allies were to move toward nuclear acquisition, that choice would no longer rest with Washington, which would lose leverage to contain or manage further proliferation. The risk of a nuclear domino effect would indeed be substantial.
Finally, beyond putting the final nail into the coffin of the non-proliferation norm, selective proliferation would inevitably erode the “post-1945 order” by accelerating arms racing and upsetting crisis stability. Confronted with nuclear-armed Germany and Japan, China and Russia would almost certainly intensify their ongoing nuclear modernization and expansion, with direct implications for the security of the United States, which would in turn feel pressure to increase its own arsenal. 
The familiar vicious cycle of arms racing would thus emerge at the intersection of regional dynamics and great-power competition, heightening the likelihood of overlapping crises and increasing the risk of nuclear use—whether through miscalculation, misinterpretation, or direct conflict arising from the unstable balance created by the emergence of new proliferators.
The United States is already grappling with the implications of a strategic environment shaped by two “near-peer” nuclear-armed competitors and the corresponding effects on its own security and deterrence posture. Accounting for the additional ripple effects generated by the emergence of three new nuclear-armed states—and the consequent adaptations by China, North Korea, and Russia—would impose yet another burden on Washington, introducing significantly greater risks and further instability.

Comprehensive Commitment to Extended Deterrence Rather Than Selective Proliferation

Selective proliferation would not only undermine the security of Canada, Germany, and Japan, but would also inflict a severe blow on the rules-based international order. As such, it cannot be promoted as a viable strategy by the United States. By advocating selective proliferation among U.S. allies, the authors implicitly assume that existing extended deterrence frameworks are insufficient to guarantee security. Rather than throwing the baby out with the bathwater, the United States and its allies can adopt a range of measures to strengthen these frameworks without resorting to the highly destabilizing option of allied nuclear proliferation.
Firstly, rather than acquiring nuclear weapons, U.S. allies should prioritize the development of advanced conventional capabilities to close existing deterrence gaps. Japan’s ongoing development of “counterstrike capabilities”, including Tomahawk and upgraded Type 12 cruise missiles⁶ , along with Germany’s participation in the European Long-Range Strike Approach (ELSA) and its announced development of a strike capability with a range exceeding 2,000 km in collaboration with the United Kingdom⁷ , exemplify the types of policies that should be pursued and encouraged. These options address identified capability gaps between U.S. allies and competitors, particularly China and Russia, in the segment of intermediate-range missiles.
Such capabilities provide greater operational flexibility and options for escalation management below the nuclear threshold. Diversifying these non-nuclear options enhances the credibility of extended nuclear deterrence itself, by avoiding an all-or-nothing response to adversary action. Moreover, they enable U.S. allies to act not merely as passive recipients of nuclear deterrence, but as active contributors to a comprehensive, conventional-and-nuclear deterrence posture.
Second, U.S. allies could provide greater conventional support for U.S. nuclear missions. Even absent direct allied involvement in nuclear decision-making, it would be critical for Washington to clarify the scope of operational planning information that can be shared with allies to enable such contributions. Drawing on NATO’s Conventional Support for Nuclear Operations (CSNO) framework or the Washington Declaration between the United States and South Korea, which called for the improvement of “combined exercises and training activities on the application of nuclear deterrence on the Korean Peninsula”⁸ , allied forces could assume a range of supporting roles. Japanese aircraft, for instance, could escort nuclear-capable U.S. bombers and fighter jets or provide air refueling, and joint exercises like the one conducted on December 10 with two U.S. B-52 bombers could take place on a more frequent and regular basis. ⁹  Similarly, Canada, Germany, and Japan could enhance their contributions to the direct support of U.S. nuclear operations through air defense systems, space and cyber capabilities, maintenance activities, and other operational support functions.
The range of possibilities for allied support demonstrates the broad potential for cooperation in strengthening extended deterrence. Such logistical and operational contributions are central to the credibility of a U.S. nuclear strike. By engaging in these activities, allies would not only reinforce deterrence but also alleviate some of the burden on the United States, while simultaneously gaining critical experience and habituation to the procedures and operations necessary to respond quickly and effectively in the event of a contingency.
Finally, allied cross-regional cooperation is essential for strengthening deterrence. It is particularly important given the possibility that China, North Korea, and Russia might support one another in crises, thereby increasing the risk of cross-theater conflict. Allies must consider horizontal escalation—across regions and domains of conflict—alongside vertical escalation when formulating responses to these adversaries. 
Because threat perceptions among allies are not uniform—Canada, Germany, and Japan assess the threats posed by China, North Korea, and Russia differently—cross-regional cooperation is vital for sharing threat assessments. Developing a common understanding of adversary capabilities and intentions is crucial to reinforce cooperation and to establish an appropriate division of deterrence labor. Such coordination would be particularly necessary in contingencies where aggression by one adversary could facilitate opportunistic aggression by another adversary in a separate theater.
In this regard, inter-theater cooperation—as exemplified by the growing Polish–South Korean defense collaboration¹⁰ —helps strengthen these exchanges and should be further expanded. Beyond shared threat assessments, effective cross-regional deterrence requires increased scenario-based planning, the establishment of collective crisis-management procedures, and the development of regular cross-regional coordination. In the conventional domain, allies can also move toward integrating production, stockpiling, and supply chains across regions to enhance resilience, optimize the division of labor by leveraging each ally’s comparative advantages, and facilitate resource allocation through clearer, shared prioritization in the event of a two-front conflict.
These measures represent realistic, near-term steps that U.S. allies can take to reinforce and expand deterrence. Since selective proliferation would not only significantly undermine their national security but also weaken the rules-based international order, these actions constitute the most feasible and effective options for simultaneously strengthening existing security mechanisms and alleviating the burden on the United States. Nuclear deterrence is not solely about nuclear weapons; rather than advocating for additional nuclear-armed states, its integration with conventional capabilities and systems must be further developed to address current threats.