VIENNA — The International Atomic Energy Agency told its 35-member Board of Governors on Tuesday that Israeli strikes and a four-week emergency inspection regime have set Iran’s uranium enrichment capability back by at least two to three years, but cautioned that a “meaningful quantity” of near-weapons-grade material remained unaccounted for and that key centrifuge components had been moved before agency teams arrived.

The 47-page report, delivered behind closed doors at the agency’s Vienna headquarters and summarized in a public statement, is the most detailed accounting yet of the damage to Iran’s nuclear infrastructure since the ceasefire took effect on April 15. It draws on 19 site visits conducted between April 18 and May 8, satellite imagery analysis, and what the agency described as “extensive, though uneven” cooperation from Iranian authorities.

“The cumulative effect of the kinetic damage and the agency’s verification activities is that Iran’s pathway to a nuclear weapon, should it choose to pursue one, has been materially lengthened,” Director General Rafael Grossi told reporters after briefing the board. “But lengthened is not closed. The board should not mistake this report for a clean bill of health.”

Grossi said inspectors had confirmed the destruction or severe degradation of enrichment halls at Natanz and the above-ground portion of Fordow, including an estimated 11,400 centrifuges, the vast majority of them advanced IR-6 and IR-9 models. The Isfahan uranium conversion facility was assessed as inoperable for at least 18 months. A previously undeclared workshop near Parchin, which Israeli officials had described as a centrifuge assembly site, was found to have been emptied of equipment in the days before it was struck.

The report’s most contested finding concerns roughly 142 kilograms of uranium enriched to 60 percent, a level just short of weapons grade. Iran declared the stockpile to inspectors before the war began. The IAEA team verified the destruction of approximately 86 kilograms in canisters recovered from the Fordow tunnel complex, but the remainder has not been located. Iranian authorities have told the agency the material was destroyed in strikes on a convoy moving it to a secure site; agency inspectors have not been permitted to visit the convoy route or examine vehicle debris.

“We are not in a position to confirm or refute the Iranian account,” the report states, in language that several Western diplomats described as unusually pointed. “Until the agency can independently verify the disposition of this material, the safeguards picture in Iran cannot be considered complete.”

Iran’s permanent representative to the agency, Ambassador Mohsen Naziri Asl, rejected what he called “selective skepticism” in remarks to the board. He said Iran had granted “unprecedented access” under the terms of the Doha framework annex and that further inspections would depend on Western states honoring sanctions-relief commitments made during the Islamabad talks. “This agency has been given more than it was promised,” he said. “It now demands more than it was promised. That is not how the Non-Proliferation Treaty was negotiated.”

The board’s response split along familiar lines. The United States, United Kingdom, France and Germany issued a joint statement calling the unaccounted material “a matter of acute concern” and urging the board to keep Iran’s file open under enhanced monitoring through at least the end of the year. Russia and China, in separate statements, praised what they called Iran’s “good-faith cooperation” and warned against using the report to justify new pressure on Tehran.

A senior State Department official, speaking on condition of anonymity to discuss the closed session, said the United States would not seek a formal censure resolution at this meeting but reserved the right to do so at the September board if “the verification gap” was not closed. “Nobody wants to throw a grenade into a ceasefire that is, so far, holding,” the official said. “But nobody is prepared to pretend 56 kilograms of HEU-adjacent material just disappeared, either.”

Israeli Prime Minister Benjamin Netanyahu, speaking in Jerusalem hours after the report’s release, said it confirmed that “Operation Rising Lion achieved its central objective” but warned that “the job is not done so long as a single canister of that material is missing.” Iranian Foreign Minister Abbas Araghchi, in a statement carried by state media, called the Israeli comments “propaganda meant to sabotage the diplomatic track” and reiterated that Iran’s nuclear program would be rebuilt for civilian purposes “on a timetable of our choosing.”

The report also documented the human cost of the strikes on the nuclear establishment. At least 187 Iranian scientists, engineers and technicians were killed across the targeted facilities, the agency said, citing Iranian government figures it described as broadly consistent with its own observations. Among the dead were five physicists previously named in IAEA reports as having held senior roles in past weapons-related research.

Analysts said the findings would shape the next phase of post-ceasefire diplomacy, including a planned follow-on round of talks in Muscat in early June. “The Iranians wanted this report to be a clean break — damage assessed, page turned,” said Layla Hassan, a Beirut-based regional analyst. “What they got is a report that says the program is broken but the file is not. That is going to make the sanctions-relief negotiation much harder than Tehran was hoping.”

Grossi told reporters he had asked Iran for access to three additional sites, including the Parchin convoy route, within 30 days. Agency officials said the next formal update to the board was scheduled for September, though an interim technical briefing could be called sooner if Iran granted the requested access or if inspectors uncovered new discrepancies.