With the risks of new nuclear-armed States on the rise, the nuclear non-profileration regime is in danger of collapse. In 2026, Iran will continue to dominate the headlines as the most likely country to exit the Non-Proliferation Treaty (NPT) or develop nuclear weapons in violation of its treaty obligations. Beyond Tehran, however, additional countries are likely to move closer to weaponization as debates about the security value of nuclear deterrence intensify and technical barriers to proliferation erode.
For decades, since the NPT entered into force in 1970, international efforts to prevent the spread of nuclear weapons proved remarkably successful. Although three countries—India, Israel, and Pakistan—developed nuclear arsenals outside of the NPT, only North Korea developed the bomb in violation of its NPT obligations. Several factors contributed to the success of nonproliferation efforts, including unity among the nuclear-weapon States in responding to proliferation threats, sustained efforts to limit the spread of technologies necessary for weaponization, and the perceived security value of the NPT.
The U.S.-led international order created a geopolitical environment conducive to these multilateral efforts to prevent proliferation. That order, however, is collapsing. In its place, a new, more dangerous geopolitical environment is emerging. Marked by fraying alliances, aggressive great-power competition, and a U.S. retreat from multilateralism, this new order could lead to a new era of proliferation, as additional States debate the value of nuclear weapons.
The changing position of the United States is a big part of the emerging nuclear proliferation landscape. The United States long sought to prevent the spread of uranium enrichment and plutonium reprocessing technologies as part of its nonproliferation strategy. Enrichment and reprocessing capabilities pose a particular risk because they can be used to produce either nuclear reactor fuel for civilian purposes or the fissile material necessary for nuclear weapons. The Trump administration, however, is loosening the decades-long bipartisan opposition to the spread of enrichment and reprocessing, increasing the risk that States will hedge or develop nuclear capabilities relevant to both weaponization and a civil energy program. Hedging gives States the option to quickly develop a nuclear deterrent if the political decision is made to do so, without necessarily violating NPT obligations.
In 2026, both South Korea and Saudi Arabia are poised to take steps toward acquiring fissile material production capabilities—with the active support of the United States. Because Seoul and Riyadh have both threatened to develop nuclear weapons in the past and the security conditions driving those threats persist, allowing or actively supporting their efforts to produce fissile material now increases the risk of these States weaponizing. It also sets a precedent that more States will follow: developing a hedge under the justification of expanding civil nuclear programs.
South Korea
In November, the Trump administration announced that the United States would support “the process that will lead to [South Korea’s] civil uranium enrichment and spent fuel reprocessing for peaceful purposes.”
South Korea has long sought enrichment and reprocessing, arguing that reprocessing is necessary to manage spent reactor fuel from its civil power program, and that enrichment will allow South Korean companies to offer nuclear fuel services with its nuclear reactor contracts, making it more competitive on the international market. When the United States and South Korea concluded a new nuclear cooperation agreement, or 123 agreement, in 2015, the Obama administration did not give in to Seoul’s push for U.S. consent to enrich and reprocess. However, it did include the option for a high-level bilateral commission to determine whether South Korea could pursue both, under certain limits, for non-military purposes. In the decade since, Washington has opposed Seoul’s efforts to exercise that option—until now.
With President Donald Trump now greenlighting South Korea’s development of these technologies, it is likely that Seoul will move quickly over the next year to negotiate parameters for enrichment and reprocessing. But even if the United States insists on limits and intrusive monitoring, developing either technology gives Seoul a quick route to producing the fissile material necessary for a bomb. Although South Korean President Lee Jae-myung has expressed opposition to nuclear weapons, some of his political opponents are pushing for weaponization. Furthermore, Seoul has an advanced ballistic missile program and produces missiles capable of delivering a nuclear warhead. Therefore, once South Korea has the capabilities to produce weapons-grade nuclear materials, it would be challenging to thwart a dash for the bomb if Seoul changes course and determines nuclear weapons are necessary.
Saudi Arabia
The United States also appears likely to support Saudi efforts to acquire the capabilities to produce fissile material in 2026, despite recent threats from Riyadh to build nuclear weapons to match any Iranian nuclear deterrent. Similar to the South Korean case, the United States initially opposed Saudi Arabia’s push to include enrichment in its nuclear cooperation agreement with the United States, delaying the conclusion of a deal. However, during a November visit to Washington, D.C., by Saudi Crown Prince Mohammed bin Salman, the United States and Saudi Arabia announced a joint declaration on civil nuclear energy cooperation, which stated that American companies will be Riyadh’s “partners of choice” for nuclear projects. A White House fact sheet on the framework did not specify if the United States will allow Saudi Arabia to domestically enrich uranium, but Saudi officials have insisted the Kingdom will not forgo enrichment as part of any deal with the United States. The Saudi position, combined with the Trump administration’s support for the South Korean enrichment program, suggests a deal with Saudi Arabia will include some type of enrichment.
Compounding this risk, reports suggest the deal might include a unique bilateral U.S.-Saudi safeguards arrangement to supplement Saudi Arabia’s legally-required monitoring arrangement with the International Atomic Energy Agency (IAEA). Previously, the United States was pushing for Saudi Arabia to sign a more intrusive monitoring arrangement with the IAEA, known as the additional protocol, which provides the IAEA with more access to nuclear sites and information beyond what the NPT requires. The U.S. move to a bilateral agreement sets a troubling precedent that States seeking nuclear weapons, or a nuclear weapons capability, may seek to exploit to negotiate less intrusive inspections in nuclear cooperation agreements.
The U.S. Congress will need to review the Saudi 123 agreement before any envisioned nuclear cooperation can go forward—and it could try to block the agreement by passing a resolution of disapproval. But it is unclear if enough members would vote against a Trump-supported agreement, despite the longstanding bipartisan congressional opposition to the spread of enrichment and reprocessing.
Beyond the specific risks of proliferation in South Korea and Saudi Arabia, relaxing conditions for domestic enrichment and reprocessing and moving away from requiring States to negotiate more intrusive safeguards arrangements with the IAEA will have long-term ramifications. Additional States debating the merits of nuclear weapons may similarly look to developing nuclear fuel cycle capabilities under the guise of civil programs to create a quicker route to weaponization. The growing interest in nuclear power to meet rising energy needs, the pursuit of nuclear-powered submarines for military purposes, or propulsion for maritime shipping could serve as justification.
Shifting Security Environment
This year is also likely to see an acceleration of the political and security conditions that make nuclear weapons appear more attractive and the pathway to weaponization more viable.
First, accountability for violating legal nonproliferation violations will likely become even more challenging. Unity in responding to proliferation threats—particularly among the five nuclear weapons States (China, France, Russia, the United Kingdom, and the United States)—was a key factor in deterring and coercing other countries from developing nuclear weapons in the past. But as that unity erodes, divisions between nuclear-weapons States over how to address proliferation risks will only grow. If non-nuclear weapon States see an opportunity to weaponize while minimizing repercussions, exiting the NPT or covertly pursuing a nuclear deterrent (or threshold status) may be more appealing. Relatedly, if States see adversaries moving toward the threshold of weaponization without consequence, it could drive their own thinking about nuclear weapons.
Specifically, at some point in 2026, the IAEA’s Board of Governors will likely move to report Iran to the U.N. Security Council for failing to implement its legally required safeguards agreement under the NPT. Iran suspended IAEA access to its nuclear sites after Israel and the United States bombed them in June. Iran has yet to allow inspectors to return to these sites or to inform the agency about its remaining stockpiles of nuclear material. The Board of Governors already censured Iran in November for failing to cooperate with the agency. It may consider reporting Iran to the Security Council as a necessary step to escalate pressure on Tehran. But it is likely that Russia, perhaps with the support of China, will veto any Security Council action against Iran, despite Tehran’s clear noncompliance. Russia and China voted against the November resolution at the IAEA and blamed the United States and Israel for creating the situation of Iranian noncompliance. The illegality of U.S. and Israeli strikes does not, however, excuse Iran from meeting its safeguards obligations.
Similarly, over the past several years, Russia and China have opposed Security Council action— including statements of condemnation—against North Korea for advancing its nuclear weapons and missile programs in violation of binding Security Council obligations to refrain from such activities. This trend, along with Russia’s blatant disregard for Security Council sanctions targeting Iran and North Korea’s nuclear program, will continue to erode mechanisms for accountability in 2026. This continued paralysis at the U.N. in responding to clear proliferation threats demonstrates to would-be proliferators that exploiting divisions amongst the Security Council’s five permanent members can mitigate the consequences of violating NPT obligations and norms.
Further exacerbating the lack of accountability is the increasingly popular idea that there is value in encouraging so-called “friendly” proliferation. For example, the United States could decide that South Korea’s pursuit of nuclear weapons would benefit U.S. security, and therefore support (or not actively oppose) its push to weaponization.
These types of arguments suggest that proliferation can be carefully controlled and fail to acknowledge the risks of a proliferation cascade, when one State’s acquisition of nuclear weapons prompts another State to follow suit. If these arguments gain traction over the next year, they risk contributing to the perception that a nuclear aspirant can minimize negative repercussions of weaponization if it frames its deterrent as beneficial to a nuclear-weapons State.
The credibility of the NPT is also likely to erode in 2026. Beginning in April, States will gather at the U.N. for the NPT Review Conference—held every five years to strengthen the treaty, including by trying to adopt a consensus “final document” that outlines specific actions for member States. Although Review Conferences have bolstered nonproliferation efforts in the past, failure to make more concrete progress on contentious issues such as nuclear disarmament are already undermining confidence in the treaty. Furthermore, the last three review conferences failed to produce final documents..
Some States are likely to use this year’s conference as an opportunity to question whether the NPT serves security interests. For example, Iran or Ukraine could press for language condemning attacks on their nuclear facilities, given the U.S. and Israeli strikes and Russia’s continued illegal occupation of the Zaporizhzhia nuclear power plant. Strong language addressing this issue could push either the United States or Russia to object to any final document. If States fail to address the issue, however, it will drive non-nuclear-weapon States to question how the NPT protects their right to peaceful nuclear activities, contributing to overall discontent with the treaty.
Similarly, some States’support for the NPT is derived in part from security benefits provided by nuclear deterrence arrangements permitted by the treaty, such as U.S. extended nuclear deterrence commitments to South Korea and Japan and U.S.-NATO nuclear-sharing arrangements, including the deployment of U.S. nuclear warheads at NATO installations in Europe. Trump’s threats to annex Greenland by force, for example, have already undermined NATO and weakened trust in the United States to honor its alliance commitments. The erosion of this credibility amid Russian nuclear sabre rattling contributes to an environment where more States may determine that national nuclear deterrents are necessary. The 2026 NPT Review Conference will likely serve as a forum for airing these concerns.
A More Dangerous World
After decades of relative success at preventing more countries from acquiring nuclear weapons, the world faces a perfect storm for that progress to be reversed. Expanding interest in nuclear energy is creating greater civilian justification to produce fissile material, while shifting security conditions are leading more States to debate the value of obtaining their own nuclear weapons. At the same time, growing divisions at the U.N. Security Council are stymieing efforts to hold States accountable to nonproliferation obligations.
It is not too late to slow, or even reverse, the erosion of nonproliferation norms, but it will take political will and creative diplomacy. In the next year, Congress should exercise its authority to review 123 agreements and ask hard questions about deals that support development of enrichment and reprocessing technologies, particularly without intrusive IAEA oversight. When agreements do not include strong nonproliferation conditions, Congress should vote to disapprove those agreements. In place of supporting national enrichment and reprocessing capabilities, the United States should support collaborative multilateral efforts to produce and manage rising demands for nuclear fuel, reducing the likelihood of a single State abusing these technologies for weapons purposes.
Domestic U.S. action alone, however, will be insufficient. Other States will need to step in to fill the leadership void created by the Trump administration’s abandonment of multilateralism to push for accountability when States violate nonproliferation norms and call out the risks of so-called “friendly” proliferation.
But absent significant efforts and policy shifts, particularly in the United States, these trends appear likely to accelerate in 2026. Although a tenth nuclear-armed State may not emerge in 2026, it is highly likely that countries such as South Korea and Saudi Arabia will move closer to developing the technical means—and the political motivation—to build a bomb.
