Japan’s review of its three strategic documents—the National Security Strategy, National Defense Strategy, and Defense Buildup Program—comes as nuclear weapons move to the foreground of Asian security. The review must address nuclear questions without forcing a premature conclusion. Japan needs a strategy that preserves credible deterrence without treating nuclear weapons as omnipotent. Japan must also strengthen its security while preserving the political and diplomatic value of its 80-year record of nuclear non-use. Tokyo’s immediate priorities are deepened consultation with Washington and stronger conventional capabilities for denial, resilience, and risk reduction. The relevant test for proposals concerning the Three Non-Nuclear Principles, an independent arsenal, or the peacetime stationing of nuclear weapons is whether they meet those operational requirements. Asymmetry vis-à-vis China remains an important consideration within this broader strategy, but cannot provide a blanket answer to every policy question.

The domestic debate has shifted, if unevenly. Prime Minister Takaichi Sanae ordered the three documents revised in 2026. In a 2024 book, she described the non-introduction principle as unrealistic. In November 2025, she initially prefaced her affirmation of the principles with “at the present stage,” but later omitted that qualifier; the Cabinet nevertheless reaffirmed them as national policy, while wording of the revised documents remains unsettled. An unnamed senior national security official reportedly raised possible Japanese nuclear possession in December 2025. Former Defense Minister Onodera Itsunori called it politically irresponsible to avoid the issue, while acknowledging current government policy. Former Foreign Minister Kono Taro argued that a pro-nuclear position should not be treated as illegitimate and called for debate. In July 2026, Defense Minister Koizumi Shinjiro urged consideration “without excluding any option,” while reaffirming the principles and US extended deterrence. These interventions widen elite debate, but the nuclear taboo still constrains public discussion.

Japan and the regional climate

As the security environment deteriorates, the security strategy review is compelling. China’s nuclear stockpile remained in the low 600s through 2024 and the Pentagon projects that it will exceed 1,000 warheads by 2030. Its increasingly survivable forces sharpen Japanese fears of decoupling as the US homeland becomes more vulnerable. North Korea combines a smaller arsenal with diverse delivery systems, compressed warning time, and a more operational posture. Russia’s nuclear threats plausibly contribute to restraint by outside powers and provide a permissive shield for conventional aggression below the highest threshold. This resembles an asymmetric form of the stability-instability paradox. Yet Russia’s arsenal has not compensated for failures in conventional planning and execution, prevented sanctions, or secured political legitimacy. Nuclear weapons deter and manipulate risk; they do not solve most of Japan’s security problems.

In considering deterrence vis-à-vis China, asymmetry is one necessary lens. China and the US-Japan alliance differ in strategic and theater assets, geography, objectives, timelines, cost calculations, and cumulative defense investment. Beijing benefits from proximity, interior lines, a dense missile force, and the ability to concentrate against exposed bases; it may also attach greater stakes to Taiwan or nearby disputes than a globally committed Washington. Japan therefore need not mirror every Chinese capability or pursue numerical parity. The objective is denying Beijing’s political aims: a rapid fait accompli, alliance paralysis, or coercive settlement under the nuclear shadow. That means slowing Chinese operations, increasing uncertainty and operational friction, and raising the political costs of aggression.

Japan’s conventional posture rests on three linked functions: survivability (dispersed, hardened bases; redundant command networks; rapid runway repair), strike-back capacity (mobile anti-ship forces, conventional counterstrike, adequate munition stocks), and situational awareness (early warning, undersea surveillance, civil preparedness). Air and missile defense and protected logistics cut across all three. Unmanned systems can complicate targeting and impose unfavorable exchange ratios. Japan’s FY2026 budget directs ¥100.1 billion ($650 million) to the SHIELD littoral-defense concept within an “asymmetrical defense architecture.” The 2026 US National Defense Strategy emphasizes homeland defense first and denial along the First Island Chain as part of its second line of effort, while omitting an explicit reference to Taiwan. Planning must distinguish a Taiwan invasion or blockade, a Senkaku gray-zone seizure, and attacks on Japan or US bases: each presents different thresholds and missions. Conventional denial prevents local faits accomplis; nuclear deterrence should address nuclear and other extreme strategic contingencies.

Extended nuclear deterrence remains indispensable, but credibility is neither automatic nor exclusively nuclear. It combines American capability and resolve, Japanese confidence, and an adversary’s assessment of alliance cohesion; more warheads address only one element. Chinese threats to the US homeland sharpen decoupling fears, while excessive nuclear dependence risks forcing an early choice between capitulation and escalation. The June 2026 Japan-US Extended Deterrence Dialogue reaffirmed the full range of US capabilities and discussed nuclear modernization and Japan’s developing strategies. The priority is institutionalizing cabinet-level consultation, shared escalation assessments, crisis exercises, agreed signaling options, and conventional responses to nuclear coercion. Nuclear weapons cannot substitute for capabilities needed to patrol gray zones, break a blockade, repair runways, counter disinformation, or sustain social cohesion. A survivable conventional posture therefore makes the guarantee more credible.

Neither an independent arsenal nor nuclear sharing offers a shortcut. A credible national force requires warheads, delivery systems, survivable basing, warning, secure command and control, trained personnel, doctrine, and authority to contemplate use. Building this takes years, creating interim vulnerability and risking alliance disruption, sanctions, diplomatic isolation, restrictions on nuclear cooperation, and regional proliferation. NATO-style nuclear sharing would provide consultation, planning, and perhaps delivery roles, but the United States would retain custody and ultimate control; forward-deployed weapons and associated bases would become priority targets. Japan would not choose such hardware sharing while seeking stronger “software” cooperation in consultation, exercises, and planning. Also, the Three Non-Nuclear Principles would remain the baseline, together with the Okada formulation that preserves exceptional political discretion over an emergency situation.

The role of technology

Technology competition must be incorporated without becoming a race for novelty. AI can support improvement of defense capabilities in such areas as logistics, maintenance, network defense, bounded analysis, sensor fusion, and unmanned systems. These applications depend on secure data and communications, reliable computing, and a procurement system able to test and field new tools. Manual fallbacks, red-teaming, auditability, and accountable human judgment remain essential.

Japan has no nuclear arsenal, but closer conventional-nuclear integration makes its own military choices relevant to nuclear escalation. Japanese sensors, bases, missile defenses, and counterstrike forces could support operations against Chinese or North Korean assets that serve both conventional and nuclear missions. Strikes on such systems—or AI-supported assessments that misidentify their function—might be interpreted as an effort to weaken an adversary’s nuclear forces. The 2024 US-China presidential understanding affirmed human control over decisions to employ nuclear weapons. Japan-US planning should identify targets and networks with nuclear significance, separate conventional and nuclear missions where feasible, and preserve time for political consultation. Extended-deterrence talks and joint exercises should address false warning, cyber disruption, and ambiguous attacks on shared command networks. Regional launch-notification and incident-management arrangements would provide an additional layer of restraint, while human authorization could remain mandatory for decisions carrying nuclear consequences.

Public legitimacy is ambivalent and potentially vulnerable. A 2023 survey found that 68.6% opposed an indigenous arsenal, 72.7% valued the Three Non-Nuclear Principles, and 85% considered US extended nuclear deterrence important. In a multiple-response question about how the international community should react to an unspecified nuclear use, only 19.2% selected nuclear retaliation. A February 2026 University of Tokyo survey likewise found more than 50% expressed reluctance or opposition to Japanese nuclear development and US nuclear deployment in Japan. These results may reflect not only a normative taboo on nuclear use, but also skepticism about dependence on nuclear weapons and doubt that deterrent threats are credible, controllable, or politically usable. That skepticism could weaken deterrence if crisis support proves shallow or alliance signals lack democratic authority. Yet Japan faces three different taboos: against nuclear use, acquisition or stationing, and open discussion itself. The first two are strong social constraints; the third can obstruct informed choice. Silence leaves policy exposed to mood swings after crises, sensational remarks, and foreign examples. Structured Diet scrutiny, scenario-based public explanation, and sustained dialogue linking Hiroshima and Nagasaki, alliance requirements, and risk reduction are therefore security requirements. The aim is neither to dissolve the taboo nor exploit it, but to prevent policy by atmosphere.

Over the next three years, Japan’s priorities are expanding munition stocks, dispersing forces, improving rapid base repair, strengthening air and missile defense, enhancing civil protection and cyber resilience, conducting alliance decision-making exercises, and developing carefully bounded uses of AI. Talks on hotlines, incident notification, and launch-notification arrangements should start immediately. Between years three and seven, the focus shifts to integrating unmanned and undersea systems, building resilient joint networks, and expanding allied industrial capacity. Formal efforts on strategic stability and arms control will take longer. Progress can be tracked through concrete indicators, including force survivability, the number of days operations can be sustained, replacement rates, decision time under attack, effectiveness of alliance consultations, public understanding, and adversary adaptation. Any move toward greater reliance on nuclear weapons requires a comparative net assessment of its marginal deterrent value, escalation risks, reversibility, diplomatic and opportunity costs, technical feasibility, and prospects for durable public consent.

Japan’s nuclear debate should move beyond the abolition and armament binary. A durable strategy begins with credible US assurance and a conventional posture designed around asymmetries Japan faces. It also requires technological and industrial capacity to sustain operations, together with practical measures to contain escalation. The Three Non-Nuclear Principles can provide political legitimacy and diplomatic leverage, provided they are sustained through informed public scrutiny rather than treated as slogans. Japan’s position as both a US ally under the nuclear umbrella and the only country to have suffered atomic bombings in war is not an anomaly to resolve. It gives Tokyo a particular responsibility to connect defense with restraint. Success can be judged by Japan’s ability to resist coercion, avert war, and retain political control in a crisis.

Possessing the bomb is the wrong measure of that achievement.

Nobumasa Akiyama ([email protected]) is Professor in the School of International and Public Policy at Hitotsubashi University and Director at the Center for Disarmament at the Japan Institute of International Affairs.

Media: Japan Ministry of Defense

The Pilot commentaries and responses represent the views of the respective authors. Alternative viewpoints are always welcomed and encouraged. Please write to [email protected] for more information on how to contribute.