By Lu Xiaoyue

Japan's Three Non-Nuclear Principles were first put forward by the cabinet of Eisaku Sato in 1967 and endorsed by the Japanese Diet in 1971. They have since served as a hallmark of Japan's "exclusively defense-oriented" policy, reflecting its status as both a country defeated in World War II and the only country ever to have suffered atomic bombings. Yet this cornerstone of Japan's nuclear policy is now coming under sustained pressure. 

The Sanae Takaichi administration is accelerating the revision of Japan's three key security documents while repeatedly floating the possibility of acquiring nuclear weapons. Of the Three Non-Nuclear Principles, the commitment not to permit nuclear weapons to enter Japanese territory presents the lowest barrier to revision—and now appears to be on the verge of being abandoned.

Following the outbreak of the Ukraine crisis in 2022, former Japanese Prime Minister Shinzo Abe repeatedly called for public discussions of a nuclear sharing arrangement with the US. Since taking office, Takaichi has departed from the practice of successive Japanese prime ministers, who publicly reaffirmed their commitment to the Three Non-Nuclear Principles. Instead, she has remained deliberately ambiguous on the issue, engaging in semantic sleight of hand by saying that Japan currently adheres to the principles while refusing to commit to maintaining them in the future.

Some in Japan have long argued that strict observance of the principle of not permitting the introduction of nuclear weapons is incompatible with the US nuclear-deterrence commitment underpinning the 1960 Japan-US Security Treaty and would weaken the effectiveness of the US "nuclear umbrella." A report submitted in March 2010 by an expert panel commissioned by Japan's Ministry of Foreign Affairs showed that Japan and the US had reached secret understandings during the Cold War that tacitly allowed US vessels carrying nuclear weapons to call at Japanese ports under certain conditions, effectively breaching the principle. Targeting this principle would not only give US nuclear-armed submarines the green light to enter Japanese ports, but could also allow US nuclear weapons to be deployed on Japanese territory in the name of "nuclear sharing." It would therefore offer the path of least resistance for undermining the Three Non-Nuclear Principles.

Using the principle of not permitting the introduction of nuclear weapons as an entry point for dismantling the Three Non-Nuclear Principles is an important step in the efforts of Japan's right-wing forces to free the country, through salami-slicing tactics, from the constraints of the postwar system. From any perspective, however, such a move would impose costs that Japan could scarcely afford.

First, it would run counter to mainstream public opinion at home. As the only country to have suffered wartime atomic bombings, Japan has developed a broad public consensus in favor of pacifism and opposition to nuclear weapons. A 2026 survey by Japan Association for Public Opinion Research found that 76 percent of respondents supported maintaining the Three Non-Nuclear Principles, while 77 percent opposed a nuclear-sharing arrangement under which US nuclear weapons would be introduced into Japan. As of August 2026, 128 Japanese local assemblies had submitted written opinions to the Diet calling on the government to uphold the principles. If the Japanese government disregards public opinion and insists on crossing this red line, it will not only trigger a strong social backlash, but also fracture Japan's postwar identity as a "peaceful nation" and shake the foundations of its political and social order.

Second, it would disrupt the regional security landscape. Northeast Asia is already one of the world's most intensely contested arenas of strategic rivalry and one of its most sensitive security environments. Any loosening of Japan's nuclear policy would inevitably alarm neighboring countries and trigger a chain reaction. More dangerously, Japan has accumulated large quantities of separated plutonium and is the world's only non-nuclear-weapon state with a complete nuclear fuel cycle. By relaxing the principle of not permitting the introduction of nuclear weapons and allowing US nuclear weapons to be deployed in the country, Japan would, in effect, use "extended deterrence" as a pretext to gain experience and establish technical pathways for developing nuclear weapons of its own. This would activate its latent nuclear-weapons capability and pose a substantive threat to regional and global security.

Third, it would contravene Japan's international obligations. The postwar arrangements embodied in the Cairo Declaration and the Potsdam Proclamation required Japan to be completely disarmed and stipulated that industries capable of enabling it to rearm for war were not to be permitted. As a non-nuclear-weapon state party to the Treaty on the Non-Proliferation of Nuclear Weapons, Japan is bound under international law not to receive, manufacture, or otherwise acquire nuclear weapons and to honor its nuclear non-proliferation obligations. Japan has spent decades cultivating its image as a "peaceful nation." If it revises the principle of not permitting the introduction of nuclear weapons and subsequently moves toward nuclear armament, it will seriously undermine the international nuclear non-proliferation regime, pose a grave threat to the postwar international order, and destroy its own diplomatic credibility.

The Japanese authorities should heed their people's calls for peace, take the security concerns of neighboring countries seriously, honor Japan's obligations under international law and its international commitments, uphold the Three Non-Nuclear Principles, and remain committed to peaceful development. This is the only right path for safeguarding Japan's long-term interests and preserving regional peace and stability.

(The author is an observer of international affairs)

Editor's Note: Originally published on huanqiu.com, this article is translated from Chinese into English and edited by the China Military Online. The information and opinions in this article do not necessarily reflect the views of eng.chinamil.com.cn.