1 September, 2025
In a world of rising geopolitical tensions and wavering traditional alliances, countries that long relied on the U.S. “nuclear umbrella” are starting to reconsider their security strategies
Contents
- Had Japan ever considered its own nuclear weapons?
- What stopped South Korea from building a nuclear bomb
- Why Japan and South Korea are again talking about nukes
- Ukraine is also considering restoring its nuclear status — but with many caveats
Recently, discussions about the possibility of developing their own nuclear weapons have reemerged in Japan and South Korea. This time, the debate is driven by Donald Trump, who, after the reelection, repeatedly questioned the U.S.’s readiness to defend not only European allies in the event of conflict with Russia but also Asian allies facing threats from North Korea and China. Statements from Trump — including criticism of NATO and demands that allies spend more on defense — have prompted Tokyo and Seoul to consider a “Plan B.”
A similar dynamic is seen in Ukraine, where the war with Russia has sparked debates over the need either to join NATO or restore nuclear capabilities. More details are reported by Espreso.
Had Japan ever considered its own nuclear weapons?
Japanese cyclotron in 1943, photo: Wikipedia
Many may find it surprising, but Japan not only considered nuclear weapons — it came close to developing them.
In the 1930s, as scientists worldwide began studying the power of the atom, Japanese researchers were also active in this field. The imperial government understood the potential of such discoveries, which could create extraordinarily powerful new bombs. Between 1941 and 1945, the Japanese army (Ni-Go project) and navy (F-Go) worked on uranium enrichment, but resource shortages, particularly uranium, halted progress. In a last-minute effort, Germany tried to deliver 560 kg of uranium oxide by submarine in 1945, but the cargo was intercepted by the U.S. It is believed that, with sufficient uranium, Japan could have built a bomb within 1–2 years, but a lack of funding and coordination during wartime made this impossible. Rumors of a Japanese nuclear test in Korea before surrender never materialized.
Overall, like their German counterparts, Japanese scientists lacked sufficient resources for their research. Both Berlin and Tokyo assumed that the Americans would likely fail to develop a bomb during WWII, so spending huge sums on it seemed unnecessary. Yet, as the Manhattan Project showed, it was possible — and Japan experienced the devastating power of nuclear weapons firsthand after the U.S. bombings of Hiroshima and Nagasaki.
After WWII, Japan embraced strong anti-nuclear policies, enshrined in its postwar Constitution and the “Three Non-Nuclear Principles” of 1967 — no production, possession, or deployment of nuclear weapons. Even though, in the 1960s, Japan’s leadership again considered nuclear options. Following China’s first nuclear test in 1964, then-Prime Minister Eisaku Sato told U.S. President Lyndon Johnson that Japan should also possess nuclear weapons for defensive purposes. Washington opposed this and secured Japan’s signature on the Nuclear Non-Proliferation Treaty. Notably, the “Three Non-Nuclear Principles” are not law; Sato explained to parliamentarians that if U.S. security guarantees ever failed, Japan might have no choice but to develop its own nuclear weapons — keeping the option open.
Japan remains unique among non-nuclear states, possessing a complete nuclear fuel cycle and advanced technologies that could support weapon development. This positions it as a “nuclear latency” country, capable of quickly producing weapons but choosing not to. For example, in 2012, Japan reportedly held 9 tons of plutonium, enough for over 1,000 nuclear warheads.
Takahama Nuclear Power Plant, photo: Wikipedia
Tokyo’s push to join the “nuclear club” was driven by events that expanded it. Rising tensions between India and Pakistan in the late 1990s led both countries to mass-produce nuclear weapons, violating the non-proliferation agreement. Japan had expected the world to respond with strong sanctions, but it did not.
Concerns grew further over North Korea’s development of ballistic missiles and nuclear weapons. When Korean missiles began flying over Japan during tests, public opinion started to shift. Japanese media, experts, and politicians increasingly called for the country to develop its own nuclear weapons.
What stopped South Korea from building a nuclear bomb
North Korea’s medium-range ballistic missile complex, which poses a threat to South Korea, photo: open sources
South Korea is also a signatory of the Nuclear Non-Proliferation Treaty and does not possess nuclear weapons. However, in the 1970s, Seoul ran a secret nuclear weapons program.
Following the Korean War, North Korea remained hostile and cooperated with the USSR and China on nuclear issues, raising security concerns in South Korea. In 1969, U.S. President Richard Nixon’s doctrine urged allies to take more responsibility for their defense. U.S. troop withdrawals from South Korea in 1971 intensified feelings of vulnerability. Under President Park Chung-hee, South Korea began secret work on uranium enrichment and plutonium reprocessing with plans to produce nuclear weapons by the late 1970s.
In 1974, the U.S. discovered the program and pressured Seoul with threats of sanctions and halted military aid. By 1975, South Korea ratified the NPT, and in 1976, Park officially ended nuclear research under U.S. assurances of protection, including the “nuclear umbrella.” The program ended but left South Korea with valuable technological expertise and infrastructure.
Concerns reemerged in the 2000s with North Korea’s nuclear and missile programs, prompting limited uranium enrichment research in South Korea — recognized as non-weapons research but raising IAEA concerns. U.S. assurances were strengthened to discourage Seoul’s nuclear ambitions.
Why Japan and South Korea are again talking about nukes
As early as March 2016, candidate Donald Trump suggested that allies like Japan and South Korea should develop their own nuclear weapons because the U.S. spends too much on their security. Initially, he did not act on this as president, but his second term raises the stakes. Russia’s full-scale invasion of Ukraine in 2022 underscored that power, not guarantees, often dictates security.
Following the invasion, former Japanese Prime Minister Shinzo Abe suggested Japan consider a nuclear-sharing agreement with the U.S., similar to NATO arrangements in Europe. Although Japan is theoretically under the U.S. nuclear umbrella, it would prefer closer deployment of weapons for faster response, especially with potential Chinese aggression toward Taiwan.
Public opinion in Japan reflects growing doubts. An April survey showed 77% of Japanese doubted the U.S. would defend Japan in a crisis; 55% saw no need for the U.S. nuclear umbrella, and 41% supported revisiting the Three Non-Nuclear Principles — up from 20% three years prior. Lawmaker Rui Matsukawa said in August: “Trump is so unpredictable, which is his strength maybe, but I think we have to always think about Plan B.”
South Korea faces even higher security risks due to North Korea. Surveys show 70–75% of the population support a national nuclear capability. Public pressure encourages political leaders to explore nuclear options. Two years ago, Seoul established a forum on national nuclear strategy to discuss security optimization. Lawmaker Choi Ji-yeon noted, “It is irrational to think another country should protect us. This is our problem and responsibility.”
However, Defense Minister Shin Won-sik warned in 2024 that creating nuclear weapons would end U.S. alliance benefits, disrupt regional power balances, and potentially harm South Korea economically. Former President Biden enhanced the U.S.-South Korea alliance to include nuclear protection against North Korean threats. But the unpredictability of Trump’s return has renewed doubts.
Ukraine is also considering restoring nuclear status — but with many caveats
A similar trend has emerged in Ukraine since the start of the full-scale war. A poll at the end of last year showed that 73% of Ukrainians support restoring the country’s nuclear status.
The poll followed Ukrainian President Volodymyr Zelenskyy’s statement to then-presidential candidate Donald Trump: either Ukraine will have nuclear weapons, or it will join NATO. The remark sparked discussion in Ukraine and internationally. BILD reported that, according to a Ukrainian official, Ukraine could build its first bomb “in a few weeks” because it has the necessary resources. Zelenskyy soon backtracked, saying Ukraine does not plan to create such weapons. Meanwhile, Russia repeatedly accused Kyiv of “creating a dirty nuclear bomb” and intensified propaganda on the issue.
The president’s statement appears to have been intended to attract attention, but it did not produce the desired result. Ukraine is neither in NATO nor does it have nuclear weapons. Instead, it seeks other security guarantees, as demonstrated by Zelenskyy’s controversial February meeting with Trump in the Oval Office. Ukraine and Europe must navigate by Trump’s rules, hoping for peace and security.
Ukrainians have learned from bitter experience that giving up real guarantees, such as nuclear weapons, for ephemeral promises — like the Budapest Memorandum — does not protect the country. When a neighbor has the largest nuclear arsenal and no one wants a military confrontation, aggression leaves the weaker side paying the highest price. That is why Tokyo and Seoul are considering their own nuclear weapons: the U.S. “nuclear umbrella” remains largely theoretical, and under Trump, unreliable.
However, developing nuclear weapons unilaterally carries risks. Alexander Bollfras, a nuclear weapons researcher at the London-based International Institute for Strategic Studies, warns that it could trigger international sanctions, reduce Western aid, and weaken Ukraine’s army.
“While nuclear weapons may superficially seem like a strong safeguard, it is difficult to imagine that the costly investment would produce an arsenal capable of containing Russia within its borders. Ukrainian nuclear proliferation after a ceasefire would be more likely to reignite the conflict than to prevent it,” Bollfras said.
He added that the “Israeli model” of security—a well-armed state under U.S. protection—is currently the most viable option for Ukraine. This is what Ukrainian authorities are pursuing by insisting on American involvement in future security guarantees. For this to happen, the war must end—but the main antagonist in the conflict shows no intention of stopping.
“Putin has wholly identified himself with the war. It’s his. As a result, his political — and possibly physical — survival depends on the war’s outcome,” The Hill notes.
Had Japan ever considered its own nuclear weapons?
What stopped South Korea from building a nuclear bomb?
Why Japan and South Korea are again talking about nukes?
These countries never needed nukes because we used to live in a different world before the cowardice of the West became so deep-seated, and prevails even in the face of constant russian and chink subversive attacks.
Then a convicted felon entered the White House who loves dictators and tyrants and wants to be one too, and thereby making everything far worse.
So, now we have a wholly different world order. The nations of ghouls are rising, while the nations of the free world have retreated into their snail houses. Of course, Japan and South Korea are part of the snail gang, simply for not having shown very much courage in this war, which, like it or not, also affects them.
Ukraine needs nukes, regardless of what some supposed experts are saying.
What a world we live in where allies are threatened with sanctions if they mention developing nukes, yet trash countries can build them unopposed.
Not to mention to bomb apartments, hospitals, schools, and shopping malls non-stop with not a worry in the world for getting any opposition from the “world policeman”.