For decades, the pursuit of weapons of mass destruction was largely confined to rogue and authoritarian regimes. Today, the discussion increasingly includes U.S. allies, signaling a profound shift in global security dynamics. The nuclear genie is out of the bottle, and conflicts in Ukraine and Iran provide valuable lessons for those considering a nuclear deterrent.
Since the mid-1960s, non-proliferation has been a cornerstone of American foreign policy. The U.S. sought to prevent “cascading proliferation,” which would destabilize global security and increase the risk of nuclear conflict. To this end, Washington extended its nuclear deterrence umbrella to allies in Europe and Asia. While this policy succeeded in many cases, it failed to prevent North Korea from acquiring WMDs and raised doubts about the credibility of U.S. deterrence.
Recent years have renewed nuclear weapons debates in Germany, Poland, South Korea, and Japan. Russia’s invasion of Ukraine and frequent nuclear threats, North Korea and China’s expanding arsenal, and weaker faith in U.S. security guarantees drive this shift. Alliances remain intact, but partners in South Korea and Europe now demand more visible, credible extended deterrence. The expiration of New START and lack of new arms control amplify these concerns.
These four countries, often mentioned as potential nuclear powers, differ significantly in their political, social, and technical contexts. Examining each highlights the diversity of challenges and considerations involved in their nuclear debates.
Germanymoving from Taboo to Debate
For years, nuclear weapons were a taboo subject in Germany. Both society and the political class rejected not only the idea of possessing nuclear weapons but also opposed participation in NATO Nuclear Sharing and the storage of U.S. warheads on German soil. However, this stance began to shift during Donald Trump’s first term, which provided arguments for proponents of acquiring an independent nuclear arsenal. The situation changed radically after Russia’s full-scale invasion of Ukraine, as support for retaining U.S. nuclear weapons in Germany suddenly exceeded 52%.
What if President Trump cuts U.S. troops dramatically in Europe instead of a mere 5000 troops in Germany and refuses to defend those who spend too little on defence? Germany is often labeled a “latent nuclear power,” but its anti-nuclear stance peaked with the 2023 closure of its last nuclear plants. Germany’s technical capacity for developing nuclear weapons remains limited, and political considerations dominate the debate.
As Liana Fix noted in Foreign Affairs, a nuclear-armed Germany could destabilize Europe rather than enhance its security. Fears of German hegemony could resurface among other European states, potentially devastating European integration. Consequently, Chancellor Friedrich Merz has rejected the idea of a national nuclear arsenal, advocating instead for a European deterrence framework based on France’s nuclear capabilities.
Poland pivoting fromMarginal Discussions to Mainstream Debate
Poland’s situation contrasts sharply with Germany’s. While Berlin has long been seen as a “latent nuclear power,” Warsaw has not. Additionally, Poland’s efforts to incorporate nuclear power into its energy mix have dragged on for decades without success. Until recently, the idea of acquiring nuclear weapons was confined to expert discussions. However, after 2022, Poland expressed interest in joining NATO’s Nuclear Sharing program, though this was rebuffed.
Unlike Germany, where domestic debate shifted with policy changes, Poland’s turning point came in 2025. Prime Minister Donald Tusk and President Karol Nawrocki publicly suggested pursuing advanced capabilities, including nuclear and unconventional weapons. Following these statements, the debate expanded significantly. By the fourth anniversary of Russia’s invasion of Ukraine, major Polish media outlets prominently featured discussions about Poland potentially acquiring nuclear weapons. Warsaw has maintained a degree of ambiguity, accepting extended French nuclear deterrence. Public opinion remains divided, with 50.2% of Poles supporting nuclear acquisition and 38.6% opposed.
South Korea as a True “Latent Nuclear Power”
South Korea remains a latent nuclear power, though Washington continues to firmly reject President Yoon’s 2023 proposals to redeploy U.S. tactical nuclear weapons or allow Seoul to develop an indigenous arsenal. As a strategic compromise, the U.S. authorized South Korea to acquire nuclear-powered attack submarines (SSNs). To align with U.S. defense-industrial interests, the construction of these submarines will take place at Philadelphia’s shipyard, leveraging the resources of South Korean firm Hanwha Ocean, which recently acquired the facility to revitalize American shipbuilding.
Ultimately, the SSN agreement is burden-sharing aimed at bolstering regional maritime security. However, it does not signal a shift in U.S. extended deterrence policy, nor does it open the door to a South Korean nuclear arsenal or a NATO-style sharing agreement. Polling by the Asan Policy Institute in April 2025 indicates that 76.2% of South Koreans support acquiring nuclear weapons—the highest level of support among the four countries considered.
Japan as a Capable but Reluctant major power
Japan, a latent nuclear state, faces political constraints and strict U.S. control over its fissile materials. Historically, Tokyo concluded the diplomatic costs outweigh military benefits, anchoring its posture by a domestic nuclear taboo, U.S. deterrence, and the Three Non-Nuclear Principles.
Former Prime Minister Kishida Fumio reaffirmed Tokyo’s commitment to these principles in his 2022 Shangri-La Dialogue speech following Russia’s invasion of Ukraine. They were also included in Japan’s 2022 National Security Strategy. Nevertheless, shifting regional threat dynamics have prompted new internal debates. Driven by growing skepticism about the reliability of U.S. extended deterrence, some defense analysts and government officials are now advocating for discussions on nuclear options. One primary proposal involves permitting the introduction of U.S. nuclear weapons into Japanese territory. While this would formally violate the Three Non-Nuclear Principles, declassified records indicate that this ban was already circumvented through secret U.S.-Japan agreements during the Cold War.
Converging Challenges
Despite their differing circumstances, all four countries would face common hurdles in pursuing nuclear weapons. First, they would need to withdraw from the NPT. Although some analysts, like Joelien Pretorius and Tom Sauer, argue that the treaty is outdated and should be replaced, leaving it would still incur serious reputational and diplomatic costs.
The next issue is securing sufficient fissile material. Without U.S. approval, this will be virtually impossible. Regardless of turmoil within the Trump administration, Washington will not permit this, except possibly to leverage Russia and China.
It is unlikely that Beijing or Moscow would view the prospect of a nuclear-armed Japan or Poland favorably. After the conflicts in Iraq and Iran, such a development would provide ample material for propaganda, highlighting American hypocrisy. Fabian Hoffmann, wondered in Internationale Politik Quarterly, questioned whether Russia might consider preemptive strikes against a potential Polish nuclear program. On the Korean Peninsula, North Korea could take various measures to seize control of the “escalation ladder.”
Germany and Poland may have options for Eurodeterrence, building deterrence around British and French nuclear arsenals. The idea is tempting but not so easy to implement. Both arsenals are based on strategic nuclear weapons, which greatly limit options. Responding to non-strategic nuclear weapons (NSNW) with strategic weapons risks rapid escalation and, instead of deterring, could lead to catastrophe.
There are also serious organizational issues. If Berlin and Warsaw were to invest in expanding the British and French nuclear arsenals, what influence—if any—would they have over the decision to use these weapons? London and Paris are not enthusiastic about transferring control of their nuclear resources to the EU or any other pan-European institution. Furthermore, the United Kingdom would first need to reduce its nuclear interdependence with the U.S.
Nuclear strategies also differ among states. Leaked Russian documents from 2024 suggest that Moscow believes it can maintain control over the escalation ladder and withstand the consequences of nuclear weapons use better than the West. Mao Zedong reportedly said that China’s large population would allow it to survive a nuclear conflict. Such a posture might be tempting for large states like the U.S. or India, but it would likely be suicidal for smaller nations. Consequently, a hypothetical Polish or South Korean nuclear doctrine would probably resemble North Korea’s.
Nuclear weapons alone are not everything; delivery systems such as ballistic and cruise missiles are also required. Among the four countries, only South Korea possesses the full range of capabilities needed to create a regional nuclear triad. This leads to questions about the rationale for acquiring nuclear weapons. The debate continues over whether NSNW is a necessity or an expensive folly.
Chinese theorists argue that technological advancements since the Cold War have redefined strategic capabilities. In their view, some non-nuclear capabilities—such as precision long-range strike systems, hypersonic missiles, space operations, and cyber capabilities—can produce strategic effects. These capabilities can undermine an adversary’s nuclear deterrence or generate large-scale effects comparable to a nuclear attack. Such advancements have created new means to limit or even prevent an adversary from conducting a nuclear retaliatory strike.
The boundary between conventional and nuclear warfare is blurring, and control over the escalation ladder is becoming increasingly difficult. Additionally, over four years of war in Ukraine, Kyiv has crossed all of Moscow’s declared red lines without provoking a nuclear retaliation. This suggests that Russia’s nuclear saber-rattling may be more about posturing than genuine intent, as Moscow has few other options left.
Dr. Paweł Behrendt PhD, Chair of the Board at the Boym Institute ([email protected]). Major areas of interest include the foreign and defence policy of Japan and China, international relations and security in East Asia, conflicts in Asia, and impact new technologies have on security.
Dr. Stephen R. Nagy ([email protected]) is Professor of Politics and International Studies at the International Christian University in Tokyo, Senior Fellow and China Project Lead at the Macdonald Laurier Institute (MLI)), and Director of Policy Studies at YCAPS. His forthcoming book, Japan as a Middle Power State: Navigating Ideological and Systemic Divides, addresses themes central to middle power strategy in the region. He is also co-author, with Michael Rosenberg, of the forthcoming Get Over It and Move On: How to Run a Global Business in the Emerging World Order.
