A fresh geopolitical controversy has erupted in East Asia after a Chinese government-linked report alleged that Japan may already possess the technological capability—and possibly even materials—to develop nuclear weapons “almost overnight.” The report, released in Beijing earlier this week, claims that Tokyo has quietly retained the option to become a nuclear-armed state despite its long-standing commitments under the Nuclear Non-Proliferation Treaty (NPT) and its Three Non-Nuclear Principles.
While Japan has officially denied any intention to develop nuclear weapons, growing regional threats, evolving defense doctrines, and controversial remarks by senior Japanese leaders have reignited debate over whether Tokyo’s nuclear restraint is permanent—or conditional.
Japan’s Anti-Nuclear Legacy
Japan’s position on nuclear weapons has historically been unequivocal. As the only country to have suffered atomic bombings, Japan signed the NPT in February 1970 and adopted the Three Non-Nuclear Principles in 1971: not possessing nuclear weapons, not producing them, and not allowing their introduction into Japanese territory.
For decades, these principles formed the moral and legal foundation of Japan’s post–World War II pacifist identity.
However, Japan’s regional security environment has deteriorated sharply. North Korea continues to expand its nuclear arsenal, China is modernizing its military at an unprecedented pace, and Russia’s invasion of Ukraine has reshaped global deterrence norms. These developments have pushed Tokyo to reassess long-standing security assumptions.
Defense Policy Shifts Signal Strategic Recalibration
Over the past decade, Japan has steadily loosened several post-war defense constraints. In 2014, it reinterpreted its constitution to allow limited collective self-defense. In 2022, Tokyo eased restrictions on acquiring long-range strike capabilities. It has also relaxed bans on exporting lethal weapons and approved record defense budgets, including a USD 58 billion allocation with plans to exceed 2% of GDP.
Most controversially, Prime Minister Sanae Takaichi has stated that a Chinese attack on Taiwan could constitute an “existential threat” to Japan—language that signals readiness for direct military involvement in a regional conflict.
China’s Allegations: “Japan Can Go Nuclear Overnight”
Against this backdrop, Beijing released a 30-page report titled “Nuclear Ambitions of Japan’s Right-Wing Forces: A Serious Threat to World Peace.” The report was jointly produced by the China Arms Control and Disarmament Association (CACDA) and a think tank affiliated with the China National Nuclear Corporation.
The report claims Japan has secretly pursued nuclear weapons research since World War II and now possesses a full nuclear fuel cycle, including reprocessing technology capable of extracting weapons-grade plutonium. It alleges Japan is the only non-nuclear state under the NPT with this capability.
Citing historical data, the report references Japan’s experimental fast reactor “Joyo,” which operated with a breeding zone capable of producing weapons-grade plutonium. According to the report—and earlier Greenpeace studies—Japan may have produced up to 40 kilograms of such material before design modifications in the 1990s.
Chinese analysts further claim Japan has stockpiled plutonium far exceeding civilian needs and maintains delivery platforms that could support nuclear weapons, including missile systems and advanced naval platforms.
Political Signals Fuel Suspicion
Chinese officials argue that recent statements by Japanese leaders validate these concerns. Prime Minister Takaichi has previously suggested that reliance on the U.S. nuclear umbrella makes Japan’s ban on nuclear weapons increasingly unrealistic. She has also openly discussed the possibility of acquiring nuclear-powered submarines.
Former Prime Minister Shinzo Abe went further in 2022 by suggesting Japan should consider nuclear-sharing arrangements with the United States, similar to NATO practices.
Additionally, anonymous remarks from senior Japanese security officials—stating that Japan should ultimately possess nuclear weapons—have amplified regional alarm, even as such views face strong domestic opposition.
Exaggeration or Strategic Messaging?
While Beijing’s report paints a dire picture, many analysts view the claims as exaggerated and politically motivated. Japan remains under strict International Atomic Energy Agency (IAEA) safeguards and continues to reaffirm its NPT commitments.
Nonetheless, experts agree that Japan’s advanced nuclear infrastructure gives it a unique “latent nuclear capability”—the technical ability to build weapons quickly if political decisions were ever made. This reality, combined with shifting rhetoric in Tokyo, has blurred the line between theoretical capacity and strategic intent.
A Nuclear Taboo Under Pressure
Public opinion in Japan remains largely anti-nuclear, shaped by historical trauma and strong civil society activism. Any formal move toward nuclear weapons would face massive domestic resistance and international backlash.
Yet, as regional security risks intensify and alliances are tested, Japan’s nuclear policy is clearly undergoing internal reassessment. Whether this results in actual policy change or remains a strategic hedge is uncertain—but the debate itself marks a historic shift.
For now, Japan officially remains a non-nuclear state. But in an increasingly volatile Indo-Pacific, even long-standing taboos are no longer immune to reconsideration.
