The statement by Japanese Defense Minister Shinjiro Koizumi calling for a “discussion without taboos” on nuclear weapons has officially brought Tokyo’s era of absolute pacifism to an end. A country that for more than half a century was the world’s leading advocate of nuclear disarmament now faces the harsh reality of 2026.

For Japan’s military establishment, Ukraine’s experience has become the main evidence that paper security guarantees and memoranda do not work. The tragedy of the Budapest Memorandum has ultimately convinced Tokyo that voluntarily giving up its nuclear potential in exchange for promises of protection is a direct path to the loss of sovereignty.

Surrounded by aggressive autocracies and increasingly questioning the reliability of the American “deterrence umbrella,” Japan is taking a historic step toward becoming a nuclear-armed state. For Tokyo, the time for compromises and illusions has irreversibly passed, while the lessons of the Russian-Ukrainian war have clearly demonstrated to the world that international law without real deterrent power cannot stop an aggressor.

Since 1967, Japan’s security policy has been based on the political doctrine of the “Three Non-Nuclear Principles,” which prohibit possessing, producing, and importing nuclear weapons. These principles were considered sacred. Today, however, the government of Prime Minister Sanae Takaichi, relying on a two-thirds constitutional majority in parliament, is openly preparing society for a change of course. The main reason is the radical revision of three key national-security documents planned for the end of the year.

Defense Minister Koizumi has stated directly that Japan cannot avoid addressing the nuclear issue. Non-nuclear status no longer guarantees survival, while the principles themselves have never been enshrined in law. They are merely a government declaration that the current Cabinet can change with a single vote.

The argument that the time has come is driven by the critical deterioration of the geopolitical situation surrounding the Japanese archipelago and three major threat factors.

First, there is the nuclear environment. Japan is surrounded by three unpredictable autocracies: China, which is rapidly expanding its arsenals; russia, which regularly conducts provocations near Japan’s borders; and North Korea, whose ballistic missiles regularly fall within Japan’s exclusive economic zone.

Second, Tokyo has carefully studied the European experience, including Finland’s example of allowing nuclear weapons to be brought onto its territory after joining NATO, as well as France’s mobilization of resources to strengthen its own strategic forces.

Third, the crisis of confidence in the United States and growing isolationist sentiments in Washington are forcing Japan’s military establishment to ask a sober question: would the United States be willing to sacrifice Los Angeles to save Tokyo? Japan is therefore increasingly considering the need to rely on itself.

Japan’s main secret is that it does not need decades to develop nuclear technology from scratch. The country is effectively a state “six months away from the bomb.” It possesses approximately 45–47 tonnes of civilian plutonium, an amount that, after further processing at the Rokkasho facilities, would technologically be sufficient to produce several thousand warheads. At the same time, the accelerated increase in the defense budget to 2% of GDP provides the necessary funding for such a program.

In addition, Japan’s space program, particularly developments based on the solid-fuel Epsilon rocket series, provides a ready technological foundation for the rapid development of military intercontinental ballistic missiles.

Japan will not secretly begin assembling a bomb tomorrow, but the roadmap from discussion to implementation is already becoming clear. At the current first stage, the discussion is being legitimized in the media and parliament in order to break the psychological barrier in a society where more than 40% of citizens already support a review of the country’s nuclear policy.

At the second stage, planned for the end of the year, the third principle prohibiting the import of nuclear weapons is expected to be officially abolished. This would allow the United States to legally deploy its nuclear forces at American bases in Okinawa or Yokosuka during crises.

The third stage, in the longer term, could involve the creation of Japan’s own minimal deterrent arsenal in response to further Chinese aggression or a worsening situation in the Taiwan Strait.

For Japan, nuclear weapons are not an instrument of expansion, but an ultimate means of preserving sovereignty. The long era of pacifism ended in 2022 with russia’s invasion of Ukraine.

The civilized world has seen that pacifism without strength merely encourages an aggressor. Tokyo is beginning to act, and the nuclear debate is the first and inevitable step toward the emergence of a new, technologically advanced nuclear power in Asia capable of deterring the ambitions of Beijing and Moscow.

Unlike Japan, Kyiv is forced to raise similar questions about nuclear deterrence not preemptively, but because of the destruction of international law and aggression.

The prospect of Ukraine restoring its own nuclear status has now entered the realm of pragmatic military planning. Unlike Japan, Ukraine would have to create production lines for weapons-grade material from scratch under wartime conditions. This would require considerable time and provoke strong opposition not only from russia but also from Western allies.

For this reason, a much more realistic scenario for Kyiv would be integration into a nuclear-sharing system modeled on NATO. The deployment of allied tactical nuclear components on Ukrainian territory is, according to expert assessments, considered the only reliable safeguard against renewed Russian aggression.

Under such a scenario, Ukraine in Eastern Europe and Japan in the Far East would become two major outposts of a new global system for deterring autocracies.

Mykola Zentsev, International Security Expert, Major General (Ret.)