Iran’s stockpile of uranium enriched to 60% purity has surged to levels that leave the international community with a shrinking window to act. The buildup, documented in the IAEA’s latest confidential reporting, represents a calculated strategy: accumulate material just below the 90% weapons-grade threshold while restricting inspector access, creating a form of nuclear leverage that stops short of an outright weapons declaration. The question facing Western capitals is no longer whether Iran can build a bomb, but how quickly it could choose to do so.
A 50% Stockpile Surge in Three Months
The scale of Iran’s recent enrichment acceleration is difficult to overstate. According to a confidential IAEA report, Iran’s stockpile of uranium enriched to 60% reached 408.6 kilograms as of mid‑May 2025, an increase of 133.8 kilograms since February. That represents a roughly 50% jump in just three months, a pace that suggests Iran has devoted significant centrifuge capacity to higher-level enrichment rather than distributing effort across lower grades. The IAEA’s quarterly report, released in late May, confirmed that Iran had amassed enough uranium enriched to a near weapons‑grade concentration, raising alarm among diplomats and nonproliferation analysts alike.
Uranium enriched to 60% is not, on its own, sufficient for a nuclear warhead. But the technical gap between 60% and 90% is far smaller than the gap between natural uranium and 60%. Most of the separative work required to reach weapons-grade material has already been completed at the 60% stage. Analysts at the Council on Foreign Relations have assessed that Iran could produce enough fissile material for a nuclear weapon in a short period if it chose to further enrich its current stockpile. What makes the current moment distinct is the combination of stockpile size and enrichment speed: Iran now possesses enough 60% material that, if further enriched, it could theoretically yield fuel for several devices, complicating any attempt to deter or reverse its progress through limited strikes or incremental diplomacy.
Inspectors Locked Out at a Critical Moment
The IAEA’s ability to verify what Iran is actually doing with its enriched uranium has deteriorated sharply. The agency reported that its lack of access to nuclear material for five months has compromised its verification capabilities. That is not a minor procedural complaint. Five months without direct access means the IAEA cannot confirm whether material has been moved, further processed, or diverted to undisclosed facilities. The agency itself has described this gap as inconsistent with standard safeguards practice and long overdue for resolution, underscoring how far the situation has drifted from the transparency that existed under the 2015 nuclear agreement.
Iran has also refused to address questions about activities at three undeclared nuclear sites, an issue the IAEA has flagged repeatedly over several reporting cycles. These concerns stem from evidence of past nuclear work that Iran has never adequately explained, including traces of nuclear material detected at locations that were never declared as part of its program. The combination of a growing stockpile and restricted access creates a verification blind spot that is qualitatively different from earlier disputes. In prior years, the IAEA could at least confirm the location and status of enriched material even when political tensions ran high. That baseline assurance has now eroded, leaving analysts to rely on indirect indicators and satellite imagery rather than on-the-ground measurements, and forcing governments to make decisions under conditions of mounting uncertainty.
Europe Declares an Impasse
The EU statement delivered to the IAEA Board on 5 March 2025 used unusually blunt language, describing the situation as an “impasse.” European diplomats noted that the IAEA cannot provide assurance that Iran’s nuclear program is exclusively peaceful, a formulation that carries significant legal and diplomatic weight under the Non‑Proliferation Treaty framework. The statement cataloged a series of specific compliance disputes: Iran’s suspension of the Additional Protocol, its reversal of modified Code 3.1 reporting obligations, its rejection of designated inspectors, and its refusal to grant access to undeclared locations that have been the subject of long‑running questions.
Each of those disputes, taken individually, might be manageable through negotiation or technical fixes. Taken together, they form a pattern of systematic obstruction that limits the IAEA’s ability to do its job. Institutions within the broader European Union system, including the foreign policy apparatus in Brussels, have framed this not as a narrow technical disagreement but as a strategic choice by Tehran to reduce transparency at the precise moment its enrichment program is accelerating. Iran, for its part, rejects the IAEA’s findings on enriched uranium and disputes the characterization of its activities as noncompliant. That rejection, however, does not resolve the underlying verification gap; it simply adds a layer of diplomatic friction to an already strained relationship and fuels calls in some European capitals for additional sanctions and censure resolutions.
Threshold Coercion as Strategy
The most common framing of Iran’s nuclear program focuses on “breakout time,” the period needed to produce enough weapons-grade material for a single device. But that framing may understate what Iran is actually doing. Rather than racing toward a bomb, Tehran appears to be pursuing what might be called threshold coercion: building a stockpile large enough to make a rapid sprint credible while stopping just short of the actions that would almost certainly trigger a military response. The 60% enrichment level is central to this strategy. It is high enough to be militarily meaningful, yet low enough for Iranian officials to insist that they have not crossed a legal red line under the NPT, allowing them to calibrate pressure on the West without openly declaring a weapons program.
This approach also gives Iran diplomatic leverage in any future talks. Reporting on back‑channel contacts has indicated that intermediaries have explored options in which Iran would cap or roll back enrichment in exchange for sanctions relief and security assurances, with one account describing how Iranian officials signaled flexibility through regional mediators. A large 60% stockpile effectively becomes a bargaining chip: Tehran can threaten to move to 90% if talks fail, or offer to dilute or export material if negotiations progress. That dynamic turns technical enrichment levels into instruments of statecraft, blurring the line between deterrence, coercion, and negotiation.
A Narrowing Window for Diplomacy
The accelerating enrichment and shrinking inspection footprint leave policymakers with a narrowing set of options. Diplomats warn that as Iran’s stockpile grows, the risk of miscalculation increases: a technical move inside a facility could be misread as a dash for a bomb, prompting pre‑emptive action. At the same time, military planners know that striking a dispersed and hardened nuclear infrastructure carries its own dangers, including retaliation across the region and the possibility that Iran would respond by openly weaponizing. The IAEA has stressed in its public messaging that restoring full monitoring is essential not only for nonproliferation, but also to prevent crises driven by worst‑case assumptions about what Iran might be doing out of sight.
For now, European governments continue to prioritize diplomatic pressure and economic measures. The European Commission and member states have kept in place a network of sanctions targeting Iran’s nuclear and missile sectors, while signaling that further steps remain on the table if Tehran continues to expand its 60% stockpile and block inspectors. At the same time, international attention is divided by other crises, from great‑power competition to regional conflicts, reducing the bandwidth available for a sustained diplomatic push. As one recent assessment from Vienna made clear, the combination of a growing stockpile, reduced monitoring, and political fatigue is steadily eroding the margin for error. Unless transparency is restored and enrichment is capped, the world may soon face a binary choice between accepting Iran as a de facto threshold nuclear state or risking confrontation to prevent it.
More from Morning Overview
*This article was researched with the help of AI, with human editors creating the final content.
