UN Nuclear Watchdog Raises Alarm Over Strikes on Iranian Nuclear Facility

On February 28, 2026, Israel and the United States launched what Washington dubbed "Operation Epic Fury" — a broad military campaign against Iran targeting its nuclear infrastructure, ballistic missile sites, and military command structures [1]. In the weeks since, the International Atomic Energy Agency has issued six updates on the situation, each more urgent than the last, warning that a radiological release "with serious consequences cannot be ruled out" [2]. On April 4, the IAEA confirmed that a projectile struck the premises of the Bushehr Nuclear Power Plant, killing one person — the closest a strike has come to an operational reactor containing 70 tonnes of nuclear fuel [3].

The campaign marks the most sustained military assault on nuclear facilities since the dawn of the atomic age, and the consequences — for international law, regional stability, and the global nonproliferation regime — are still unfolding.

What Was Struck and What Was Damaged

The strikes have targeted Iran's nuclear infrastructure across multiple sites over two distinct phases.

Phase One — June 2025: Israeli and U.S. forces struck the above-ground Pilot Fuel Enrichment Plant at Natanz, rendered the Fordow Fuel Enrichment Plant inoperable, and blocked tunnel entrances at the underground storage facility in Isfahan, where Iran had moved much of its highly enriched uranium stockpile [4]. Satellite imagery analyzed by the Bulletin of the Atomic Scientists showed a truck loaded with 18 containers, likely transporting highly enriched uranium, outside Isfahan's south tunnel entrance on June 9, 2025 — days before the strikes began [5].

Phase Two — February–March 2026: Operation Epic Fury expanded the target list. Natanz was struck again, with the IAEA confirming damage to entrance buildings at the underground Fuel Enrichment Plant, though the core underground facility survived [6]. Israel's military claimed it struck the Min Zadei facility northeast of Tehran, which it described as a site where Iran was "secretly developing a critical nuclear weapons component" [1]. Projectiles hit near the Bushehr Nuclear Power Plant on at least four occasions — February 28, March 17, March 24, and March 27 — according to Iran's Foreign Minister Abbas Araghchi [3].

Source: Arms Control Association / IAEA Reports

Data as of Apr 4, 2026CSV

The IAEA assessed that no radiological release occurred from the enrichment facility strikes, stating there was "no radiological consequence expected and no additional impact detected at FEP itself" [7]. But as the strikes moved closer to the operational Bushehr reactor, the agency's tone shifted markedly. Rosatom CEO Alexey Likhachev warned that a direct hit on Bushehr "would certainly be a regional-scale disaster" [8].

The Radiological Gamble: What's at Stake

The distinction between enrichment facilities and operational nuclear reactors is central to the risk calculus. Enrichment plants at Natanz and Fordow process uranium hexafluoride gas in centrifuge cascades — hazardous, but not comparable to the radioactive inventory of a power reactor. Bushehr, by contrast, contains approximately 210 tonnes of spent nuclear fuel and around 70 tonnes of fuel in its active reactor core [8].

The civilian population within the immediate risk zone is relatively small around Natanz — the nearby town had a population of about 14,122 as of the 2016 census [9]. Iranian authorities denied reports that an evacuation had been ordered [10]. But Bushehr sits on the Persian Gulf coast, and the downwind geography raises concerns that extend far beyond Iran's borders.

Kuwait City is 175 miles from Bushehr. Manama, Bahrain's capital, is 187 miles away. Doha is 254 miles distant, and Dubai 373 miles [8]. Prevailing northwesterly winds could carry radioactive material directly toward these population centers. Gulf states depend almost entirely on desalinated seawater — a contamination event in the Persian Gulf could compromise drinking water supplies for millions [8].

Rosatom began evacuating its personnel from Bushehr in early March, eventually withdrawing more than 200 staff while leaving a skeleton crew of "volunteers" to maintain reactor operations [11]. The parallel with Russia's Zaporizhzhia Nuclear Power Plant in Ukraine — another Rosatom-linked facility caught in a war zone — has not been lost on nuclear safety analysts [8].

Iran's Enrichment Program: Disrupted but Not Destroyed

Before the June 2025 strikes, Iran had accumulated 440.9 kg of uranium enriched to 60% U-235 — measured by the IAEA in its September 2025 verification report [12]. At 60% enrichment, this material is a short technical step from the 90% weapons-grade threshold. The Institute for Science and International Security estimated that Iran could convert its 60% stockpile into approximately 233 kg of weapons-grade uranium — enough for roughly nine nuclear warheads — in as little as three weeks at Fordow [12].

Source: IAEA Verification Reports / ISIS Analysis

Data as of Mar 1, 2026CSV

The strikes appear to have reduced the accessible stockpile significantly. The Arms Control Association estimated that approximately 200 kg of 60%-enriched uranium remains accessible at Isfahan's underground facility, with an additional 200-plus kg either destroyed, compromised, or inaccessible at Natanz and Fordow [4]. U.S. intelligence reportedly assessed with "high confidence" that Iran could access the Isfahan material only through a small opening, and that any removal attempt would be detected [4].

But Iran's enrichment capability — as distinct from its existing stockpile — remains largely intact. The IAEA acknowledged it "lost continuity of knowledge regarding Iran's centrifuge production in 2021," and between 2021 and June 2025, Iran manufactured more centrifuges than it reported installing at declared sites [4]. The knowledge base for enrichment is indigenous, and centrifuge production can resume once facilities are repaired or relocated.

As of March 2, 2026, IAEA Director General Rafael Grossi told the Board of Governors that his agency had "not had access to Iran's previously declared inventories of low-enriched uranium and high-enriched uranium (over 20%) for more than eight months, making their verification — according to standard safeguards practice — long overdue" [13]. The IAEA has not been granted access to any of the bombed sites to confirm the extent of damage or verify the location and condition of nuclear material [4].

The Legal Battlefield

Attacking nuclear facilities raises immediate questions under international humanitarian law. Article 56 of the 1977 Additional Protocol I to the Geneva Conventions prohibits attacks on "nuclear electrical generating stations" when such attacks "may cause the release of dangerous forces and consequent severe losses among the civilian population" [14].

However, this provision applies narrowly to nuclear power stations — not enrichment facilities. Legal scholars at the University of Pennsylvania's Center for Ethics and the Rule of Law argued that Israel's strikes on Natanz, Fordow, and Isfahan fall outside Article 56's scope [15]. They further noted that Israel, the United States, and Iran are all non-signatories to Additional Protocol I, limiting its direct legal force [15].

The broader question is whether the strikes constitute lawful self-defense under Article 51 of the UN Charter. Proponents argue that ongoing hostilities between Israel and Iran — including Iran's April 2024 barrage of over 300 drones and missiles and its October 2024 attack with more than 180 ballistic missiles — established a continuous armed conflict, removing the need for an "imminent threat" test before each subsequent action [15].

Even under the more restrictive anticipatory self-defense framework, supporters contend the standard was met: Iran's breakout time had reportedly shrunk to approximately one week, the IAEA had confirmed "non-compliance" and rapid accumulation of highly enriched uranium, and Iranian leadership had made explicit threats to "annihilate" Israel while developing nuclear-capable delivery systems [15].

Critics reject this framing. International law scholars have long distinguished between anticipatory self-defense — responding to an imminent attack — and preventive war — striking to prevent a future capability. The customary international law standard, derived from the 1837 Caroline affair, requires that the necessity of self-defense be "instant, overwhelming, leaving no choice of means, and no moment of deliberation" [16]. Striking a country's nuclear infrastructure based on projected enrichment timelines and intelligence assessments falls, in many scholars' view, on the preventive side of that line [17].

The IAEA itself stated that while Iran had an "ambitious" nuclear program and had refused inspections, "there was no evidence of a structured nuclear weapons program when the 2026 war began" [1].

Historical Precedents: Osirak, Al-Kibar, and the Paradox of Strikes

Israel has struck nuclear facilities twice before. In 1981, Israeli jets destroyed Iraq's French-built Osirak reactor near Baghdad. In 2007, Israel bombed Syria's Al-Kibar reactor, built with North Korean assistance.

The outcomes diverge sharply. The Osirak strike, initially condemned unanimously by the UN Security Council, the General Assembly, and the IAEA Board of Governors, paradoxically accelerated Iraq's nuclear weapons program [18]. Freed from French oversight and international monitoring, Saddam Hussein launched a secret decade-long effort to build a uranium bomb using electromagnetic isotope separation and centrifuge technology [18]. By 1991, Iraq was far closer to a weapon than it had been before the strike.

The Al-Kibar case is often cited as a success. Syria lacked the indigenous scientific capacity to rebuild, and the attack effectively ended its nuclear ambitions — though evidence later emerged that the Assad regime may have continued nuclear activities elsewhere [19].

Iran's program more closely resembles the post-Osirak scenario than the Al-Kibar one. Its nuclear infrastructure is distributed across dozens of sites, much of it buried deep underground. Its scientific workforce numbers in the thousands, and its centrifuge technology is domestically developed. As the Arms Control Association assessed: "Iran will retain the nuclear expertise and likely key materials necessary for building a nuclear bomb" regardless of the strikes' immediate impact [4].

The Intelligence Question: How Close Was Iran?

The strategic case for the strikes rested on the claim that Iran was approaching a nuclear weapons capability that would fundamentally alter the Middle East's security landscape.

At the February 24, 2026, State of the Union address, President Trump stated that Iran had "restarted its nuclear program" and was "developing missiles capable of striking the US" [1]. The Foundation for Defense of Democracies argued that the strikes were necessary to "end Tehran's nuclear weapons program," pointing to the shrinking breakout timeline and Iran's accumulation of 60%-enriched uranium [20].

Independent nonproliferation experts offered a more measured assessment. The IAEA's position was that despite Iran's advanced enrichment activities, there was no confirmed evidence of an active, structured weapons program at the time the war began [1]. The distinction between capability and intent — between possessing the technical means to build a weapon and a political decision to do so — remained unresolved.

The breakout timeline is often misunderstood. Iran's ability to enrich its 60% stockpile to weapons-grade in three weeks refers only to the fissile material component. Building a deliverable nuclear warhead requires additional steps — weaponization design, testing, and mating a device to a delivery system — that intelligence agencies estimated could take one to two years beyond the acquisition of weapons-grade material [4].

The Stuxnet Lesson: Do Strikes Cause Doubling Down?

History offers a consistent pattern: covert and military operations against Iran's nuclear program have slowed it temporarily while strengthening the political consensus within Iran to pursue nuclear capability.

The Stuxnet cyberattack, discovered in 2010, destroyed nearly one-fifth of Iran's centrifuges at Natanz [21]. Between 2010 and 2012, four Iranian nuclear scientists were assassinated in Tehran, with Iran accusing the CIA and Mossad [22]. Neither Stuxnet nor the assassinations halted the program. Instead, the killings prompted students in other fields to switch to nuclear science, and Iran's enrichment activities continued to expand [23]. As Responsible Statecraft reported, "none of the acts of assassinations and sabotage, with the possible exception of the Stuxnet attack, has appreciably slowed Iran's missile and nuclear programs. The science has become indigenous" [23].

The diplomatic track showed more durable results. The 2015 Joint Comprehensive Plan of Action (JCPOA) froze Iran's enrichment at 3.67% and reduced its stockpile by 98%, with intrusive IAEA verification [24]. Iran's stockpile of 60%-enriched uranium was zero as recently as June 2019. The rapid accumulation that followed — from zero to over 440 kg in six years — came after the U.S. withdrawal from the JCPOA in 2018.

The question now is whether military action will prompt Iran to cross the threshold it has so far stopped short of: an explicit decision to build a nuclear weapon. The historical evidence from Iraq, the pattern following Stuxnet, and Iran's own trajectory since 2018 all point toward military strikes reinforcing, rather than eliminating, proliferation incentives [19].

Oil Markets and Global Fallout

The war's economic consequences have been immediate. WTI crude oil prices surged from roughly $58 per barrel in late February to over $104 by late March 2026 — a 45.7% year-over-year increase — as fighting disrupted traffic through the Strait of Hormuz, through which roughly 25% of the world's oil and gas supply passes [25].

Source: FRED / EIA

Data as of Mar 30, 2026CSV

The broader nonproliferation implications extend well beyond Iran. Academic research on nuclear nonproliferation spiked to 1,467 publications in 2023, reflecting growing concern about the framework's durability even before the current conflict [26]. If the strikes ultimately push Iran toward a weapon, the cascade effects could include nuclear hedging by Saudi Arabia, Turkey, and Egypt — each of which has expressed conditional interest in nuclear capability in the past.

Source: OpenAlex

Data as of Jan 1, 2026CSV

What Comes Next

The IAEA remains locked out. Iran's enrichment knowledge is intact. Approximately 200 kg of 60%-enriched uranium sits in underground tunnels at Isfahan, beyond the reach of current military operations. Bushehr's reactor continues to operate with a skeleton crew, and projectiles continue to fall nearby.

The strikes have destroyed infrastructure, degraded access routes, and reduced accessible fissile material stockpiles. They have not eliminated Iran's ability to enrich uranium, its scientific workforce, or its centrifuge manufacturing knowledge. Whether they have strengthened or weakened the case for an eventual Iranian nuclear weapon depends on a political calculation in Tehran that no bomb, bunker buster, or intelligence assessment can resolve from the outside.