IAEA Iran Monitoring Report Analysis

Background

• This report summarizes and assesses information in the International Atomic Energy Agency's (IAEA's) quarterly report, dated May 31, 2025, Verification and monitoring in the Islamic Republic of Iran in light of United Nations Security Council resolution 2231 (2015), including Iran's compliance with the Joint Comprehensive Plan of Action (JCPOA). This report also includes a few of the findings in the IAEA's parallel report, Iran NPT Safeguards Agreement with the Islamic Republic of Iran.
• Although this report and the parallel NPT report serve to highlight Iran's multiple violations of the JCPOA and the NPT and its increased capabilities to make weapon-grade uranium, they obscure perhaps the most critical concern. Iran's nuclear weaponization program is steadily making progress, out of sight of the inspectors and the world. The urgent need is to place IAEA inspections at heart of relations with Iran and reaffirm that Iran will never be allowed to get a nuclear weapon.

Findings

• Iran can convert its current stock of 60 percent enriched uranium into 233 kg of WGU in three weeks at the Fordow Fuel Enrichment Plant (FFEP), enough for 9 nuclear weapons, taken as 25 kg of weapon-grade uranium (WGU) per weapon.
• Iran could produce its first quantity of 25 kg of WGU in Fordow in as little as two to three days.
• Breaking out in both Fordow and the Natanz Fuel Enrichment Plant (FEP), the two facilities together could produce enough WGU for 11 nuclear weapons in the first month, enough for 15 nuclear weapons by the end of the second month, 19 by the end of the third month, 21 by the end of the fourth month, and 22 by the end of the fifth month.
• In front of the inspectors' eyes, Iran is undertaking the near-final step of breaking out, now converting its 20 percent stock of enriched uranium into 60 percent enriched uranium at a greatly expanded rate, although this rate cannot be sustained much longer (see below).
• Iran has no civilian use or justification for its production of 60 percent enriched uranium, particularly at the level of hundreds of kilograms. Its rush to make much more, quickly depleting its stock of near 20 percent enriched uranium, which has a civilian use in research reactors, raises more questions. Even if one believed the production of 60 percent is to create bargaining leverage in a nuclear negotiation, Iran has gone way beyond what would be needed. One has to conclude that Iran's real intent is to be prepared to produce large quantities of WGU as quickly as possible, in as few centrifuges as possible.
• Not surprisingly, and in its understated style, the IAEA reiterated in this most recent report: "The significantly increased production and accumulation of highly enriched uranium by Iran, the only non-nuclear-weapon State to produce such nuclear material, is of serious concern."
• Because of the greatly expanded production of 60 percent enriched uranium, the IAEA previously requested and received permission for strengthened safeguards at Fordow.
• The IAEA also previously reported the implementation of a "strengthened safeguards approach […] at a nuclear material storage at Esfahan", an important development given that a large amount of Iran's 60 percent HEU and 20 percent enriched uranium stock have previously been reported to be stored at Esfahan. Exactly how much of Iran's enriched uranium stocks are held at Esfahan, however, compared to other locations, is no longer reported.
• The IAEA's efforts to verify Iran's nuclear activities, particularly its uranium enrichment activities, continue to be seriously affected by Iran's decision last fall to withdraw the designation of several experienced inspectors. The IAEA repeatedly requested that Iran reconsider this inappropriate, political act, including in a June 2024 Board of Governors censure resolution, but Iran has not done so. The IAEA stated in its accompanying report, NPT Safeguards Agreement with the Islamic Republic of Iran: "The withdrawal of the designation of several experienced inspectors was also not in line with the required spirit of cooperation."
• As of May 17, 2025, the net overall enriched uranium stock, including all levels of enrichment and all chemical forms, had increased by 953.2 kg, from 8294.4 kg to 9247.6 kg (Uranium mass or U mass).
• As of May 17, Iran's stockpile of 60 percent HEU in the form of uranium hexafluoride was 408.6 kg (as measured in U mass) or 604.4 kg (hex mass). This represents a net increase in the stock in the form of uranium hexafluoride of 133.8 kg (U mass) since the previous reporting period. It does include 6.5 kg of enriched uranium (U mass) that is assessed to be enriched above 20 percent but far below 60 percent, as it was discharged from the cascade into a dump tank rather than collected as product.
• Since December 5, Iran has been using 20 percent feedstock rather than 5 percent feedstock to produce 60 percent HEU in the two interconnected IR-6 cascades used for 60 percent HEU production since November 2022. This change led to an average monthly production of 33.5kg 60 percent HEU at Fordow during this most recent reporting period. The two IR-6 cascades used include one of which is easily modifiable to change operations and enrich uranium to higher levels.
• Iran continued to produce 60 percent HEU from 5 percent low enriched uranium (LEU) feed in two pairs of interconnected advanced centrifuge cascades at the above-ground Pilot Fuel Enrichment Plant (PFEP).
• Adding the average monthly production of 60 percent HEU at the PFEP, which slightly increased to 4kg per month, Iran is producing 37.5 kg (U mass) or 55.5 kg (hex mass) of 60 percent enriched uranium per month on average. It could produce about 675 kg (hex mass) or 456 kg (U mass) of near 60 percent enriched uranium per year.
• However, in multiplying its 60 percent HEU production, Iran is using significant amounts of 20 percent enriched uranium as feedstock, a rate which is not sustainable unless Iran significantly increases 20 percent enriched uranium production. It used an average of 117 kg (U mass) of 20 percent enriched uranium as feed per month, compared to an average monthly production of 14 kg.
• This led to a reduction in Iran's near 20 percent enriched uranium stock in the form of uranium hexafluoride of 332.3 kg (U mass), for a total stock of 274.5 kg (U mass) as of May 17, 2025.
• At this feed and production rate, Iran could sustain the high 60 percent HEU production for approximately three months after May 17.
• Iran now has nearly 14,689 advanced centrifuges installed at Natanz and Fordow, where most are deployed at the Natanz Fuel Enrichment Plant (FEP).
• Including the installed IR-1 centrifuges at the FEP, PFEP, and FFEP brings the total number of installed centrifuges to roughly 21,900. It should be noted that many advanced centrifuges are deployed but not enriching uranium, and the IR-1 centrifuges have a reduced ability to enrich uranium.
• During the reporting period, Iran installed five new IR-4 cascades at Natanz, for a total of 23 total IR-4 cascades, 12 of which are operating.
• Iran made no progress in this reporting period on installing the massive cascade consisting of 1152 IR-6 centrifuges.
• The quantity of Iran's enriching centrifuges increased during this reporting period, to approximately 18,000 centrifuges.
• Iran has a total installed enrichment capacity of roughly 64,000 swu/year. Its enriching centrifuge capacity is less, approximately 50,000 swu/year.
• Iran's stockpile of near 5 percent LEU in the form of UF6 increased by 1853.4 kg (U mass) from 3655.4 kg to 5508.8 kg (U mass), or 8149.1 kg (hex mass).
• In general, Iran has not prioritized stockpiling uranium enriched between 2 to 5 percent. This choice is at odds with Iran's contention that its primary goal is to accumulate 4 to 5 percent enriched uranium for use in nuclear power reactor fuel. Instead, Iran has focused on producing 60 percent enriched uranium, far beyond Iran's civilian needs.
• The IAEA again reports that Iran will not start commissioning of the Arak reactor, now called the Khondab Heavy Water Research Reactor (KHRR), or IR-20, until at least 2025, with operation expected to start in 2026. Inspectors again did not observe any significant changes at the reactor, noting this time only minor civil construction.
• Iran stopped implementing the Additional Protocol (AP) to its comprehensive safeguards agreement (CSA) and the JCPOA's additional monitoring arrangements on February 23, 2021. Iran's actions and its refusal to cooperate with the IAEA across a wide range of monitoring issues causes the IAEA to consistently express doubt about understanding key aspects of Iran's nuclear activities. Without the AP in place, the IAEA has neither been able to conduct complementary access to any sites and other locations in Iran nor received updated declarations from Iran.
• The IAEA reports that it has "lost continuity of knowledge in relation to the production and current inventory of centrifuges, rotors and bellows, heavy water and UOC [uranium ore concentrate], which it will not be possible to restore."
• The IAEA concludes that "Iran's decision to remove all of the Agency's equipment previously installed in Iran for JCPOA-related surveillance and monitoring activities has also had detrimental implications for the Agency's ability to provide assurance of the peaceful nature of Iran's nuclear programme."
• Although the IAEA can ascertain the number of centrifuges deployed at Fordow and Natanz, it cannot know how many more Iran has made and stored or deployed at an undeclared site. A risk is that Iran will accumulate a secret stock of advanced centrifuges, deployable in the future at a clandestine enrichment plant, which would only need to house a relatively few advanced centrifuge cascades to enrich Iran's current stock of 60 percent HEU to WGU. At the least, this situation complicates any future verification effort and contributes to uncertainty about the status of Iran's nuclear activities and facilities.
• Combined with Iran's refusal to resolve outstanding safeguards violations and the program's unresolved nuclear weapons dimensions, the IAEA has a significantly reduced ability to monitor Iran's complex and growing nuclear program. The IAEA's ability to detect diversion of nuclear materials, equipment, and other capabilities to undeclared facilities remains greatly diminished.

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