Beware the dangerous signals of Japan's nuclear "unshackling"

On July 17, Japanese Minister of Defense Shinjiro Koizumi stated on a right-wing online program that Japan should discuss nuclear weapons-related policies without any taboo, including whether to revise the three non-nuclear principles that it has upheld since WWII. Citing European countries' adjustments to their national security strategies in the wake of the Ukraine conflict, he argued that Japan must face up to reality and act boldly. As the incumbent defense minister, Koizumi's remarks represent yet another dangerous attempt by Japan's right-wing forces to push for nuclear "unshackling". It undoubtedly calls for the vigilance of the international community.

Internationally, legally binding documents under international law—including the Cairo Declaration, the Potsdam Proclamation and the Japanese Instrument of Surrender—prohibit Japan from maintaining any military capabilities usable for re-arming for war, and bar it from embarking on the path of nuclear armament. Meanwhile, as a non-nuclear-weapon state party to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT), Japan must abide by the provisions of "not receiving, manufacturing, acquiring or transferring nuclear weapons."

Domestically, the three non-nuclear principles—not possessing, not producing and not permitting the introduction of nuclear weapons—were enacted by the Japanese Diet in 1971 as a solemn commitment to the international community. Article 9 of the Constitution of Japan, which entered into force in 1947, stipulates that the Japanese people forever renounce war as a sovereign right of the nation. The Atomic Energy Basic Law of Japan also restricts nuclear energy utilization to peaceful purposes.

In disregard of established legal principles while using "security" as a pretext, Shinjiro Koizumi seeks to break through the three non-nuclear principles. His move underscores Japan's inclination to subvert the post-war international order and even revert to militarism. On various international occasions, he claimed that Japan has abided by its "exclusively defense-oriented policy", pursued "peaceful development" and upheld the three non-nuclear principles. Yet at home, he has openly called for "discussing nuclear weapons policies without any taboos". Such self-contradiction has stripped away Japan's pretense and exposed its lies intended to deceive the international community.

Japan's stoking of "security anxiety" is in fact a political ploy to exploit the issue and advance its remilitarization agenda. As Europe is faced with direct geopolitical conflict, Koizumi deliberately drew a parallel between Japan's situation and European countries' policy shifts after the Ukraine conflict broke out. However, this line of reasoning is totally untenable.

Koizumi and the right-wing forces behind him have repeatedly made false claims about the so-called "China nuclear threat". This is merely a pretext for Japan to seek nuclear "unshackling". The truth is, China follows the path of peaceful development and pursues a defensive national defense policy. Its nuclear forces have been kept at the minimum level necessary for national security. China has committed to a "no first use of nuclear weapons" policy, and will not use or threaten to use nuclear weapons against non-nuclear-weapon states or nuclear-weapon-free zones. It poses no threat to Japan.

For Japan, the real security risk does not come from outside, but from its own dangerous moves of continuously breaching the pacifist constitution and expanding its military buildup.

The Japanese government's gradual push for nuclear "unshackling" runs counter to mainstream public opinion in Japan. Multiple polls show that around 70 percent of the Japanese public supports sticking to the three non-nuclear principles. In a poll by the Jiji Press in January 2026, 62.6 percent of respondents opposed Japan's possession of nuclear weapons, while only 16.7 percent were in favor. A poll by the Asahi Shimbun in April found that 75 percent of respondents believed the three non-nuclear principles should be maintained.

Compared with its predecessors, the Takaichi administration has seen a sharp rise in written submissions from local assemblies urging the government to uphold the three non-nuclear principles. As the only country that suffered atomic bombings, the tragic history of Hiroshima and Nagasaki should have formed a cornerstone of Japan's non-nuclear stance. Yet some Japanese politicians are turning their backs on this historical lesson, and peddling dangerous narratives such as "nuclear sharing" and "nuclear deterrence". This not only contradicts the spirit of the pacifist constitution, but also defies domestic public opinion.

Once Japan achieves nuclear "unshackling", it will spark a regional security crisis. The danger lies not only in its violation of international law, but also in the chain reaction it could set off.

Among all the non-nuclear-weapon state parties to the NPT, Japan is the only one that masters reprocessing technology and has the capability to extract weapons-grade plutonium. By the end of 2024, Japan's stockpile of separated plutonium under its control at home and abroad had reached 44.4 tonnes, paving its way for a rapid "nuclear breakthrough". In addition, Japan boasts a complete nuclear fuel cycle system and substantial reserves of nuclear delivery technologies.

Should Japan give up the three non-nuclear principles, allow US nuclear-capable warships and aircraft to enter its territory, or advance "nuclear sharing", it would upend the strategic balance in Northeast Asia. This would not only prompt its neighboring countries to take countermeasures and fuel a regional arms race, but also raise the risks of nuclear miscalculation and nuclear confrontation. More seriously, as a major economic and technological power, Japan's nuclear "unshackling" would set a damaging precedent for non-nuclear-weapon states worldwide to cross the nuclear threshold, putting the global nuclear non-proliferation regime at risk of collapse.

Shinjiro Koizumi's remarks are by no means an isolated incident. Since Sanae Takaichi took office, calls for a reassessment of the three non-nuclear principles have been mounting in Japanese politics. The Japanese government is seeking to strengthen extended deterrence cooperation with the United States by revising its three security documents.

A series of developments show that Japan's right-wing forces are using salami-slicing tactics to erode the bottom line of the post-war peace framework. Peace is not easy to come by. Once the Pandora's box of nuclear proliferation is opened, it will spell endless trouble. The international community must remain highly vigilant and resolutely prevent Japan from going further down the path of nuclear armament.

The author is an Assistant Research Fellow at the Institute of Japanese Studies of the Chinese Academy of Social Sciences