Israeli strikes during the six-week war destroyed an estimated 70 to 85 percent of Iran’s installed enrichment capacity at the Natanz and Fordow complexes, according to a preliminary International Atomic Energy Agency assessment circulated to member states on Wednesday, a finding that has scrambled the negotiating posture in Vienna and handed the most consequential piece of paper to land on diplomats’ desks in the two weeks since the ceasefire took hold.

The 14-page technical summary, dated April 28 and obtained by several wire services from a European delegation in Vienna, draws on three days of inspector work at Natanz, two at Fordow and a partial visit to the Parchin military complex outside Tehran. It concludes that the underground IR-6 production hall at Natanz “sustained catastrophic damage to cascade alignment and vacuum integrity,” that the Fordow facility’s deeper galleries “appear to remain structurally intact but were rendered inoperable by direct hits on power and cooling infrastructure,” and that “no evidence” was found of clandestine enrichment activity since the April 15 cessation.

A senior IAEA official, speaking on condition of anonymity because the report has not been formally released, said the agency’s inspectors had recovered approximately 230 kilograms of low-enriched uranium hexafluoride from a sealed buffer storage area at Natanz, accounting for roughly two-thirds of the material that Iran had declared was on site in its last formal inventory in January. The remaining one-third, the official said, is presumed either destroyed, dispersed in the strikes, or moved to an undisclosed location before the war.

“The headline of the report is not the destruction. The headline is the gap,” said Dr. Olli Heinonen, a former IAEA deputy director general now at the Stimson Center in Washington, in a telephone interview. “Eighty kilograms of LEU is unaccounted for. That is not a weapons quantity, but it is the kind of bookkeeping problem that makes the next agreement very hard to write.”

The findings landed in Vienna on the second morning of the post-ceasefire ministerial round at the Palais Coburg, where Saudi and Emirati envoys joined American, European, Chinese and Russian counterparts in pressing Iran on a successor framework to the lapsed 2015 nuclear deal. According to two diplomats familiar with Tuesday night’s session, the U.S. delegation had been briefed on the preliminary findings in advance and had recalibrated its written verification expectations overnight, narrowing earlier demands for “continuous monitoring” at six sites into a tighter list focused on three: Natanz, Fordow and an Isfahan facility that has long been flagged by the agency.

IAEA Director-General Rafael Mariano Grossi, addressing reporters in Vienna shortly before noon, called the report “an honest first picture” and cautioned that it should not be read as either an exoneration or an indictment. “Iran has cooperated. The damage is severe. The accounting is incomplete,” he said. “Each of those facts is true at the same time.”

Iranian officials reacted carefully. Foreign Minister Abbas Araghchi, in remarks at the Iranian mission in Vienna, said the report “vindicates what Iran has said from the beginning,” namely that the country’s program was civilian in character and that the missing material had been “destroyed by Israeli aggression, not hidden by Iranian intent.” He declined to address the Isfahan question directly, saying only that “every reasonable verification request will receive a reasonable answer.” Behind the public statement, two members of the Iranian delegation acknowledged to Western counterparts in a side conversation that Tehran would accept short-notice inspections at Isfahan if the United States and the European Union moved on the first tranche of frozen-asset releases under negotiation in Geneva, according to a European diplomat briefed on the exchange.

In Jerusalem, Prime Minister Benjamin Netanyahu’s office issued a terse statement saying the report “confirms the operational success of the Israeli campaign” but warned that “the work of preventing an Iranian bomb is not complete and will not be entrusted to inspectors alone.” Israeli Foreign Minister Gideon Sa’ar, in a separate appearance at a Tel Aviv security conference, said Israel would judge the Vienna outcome “by what is verified, not what is signed.”

The 80-kilogram discrepancy quickly became the dominant subject of Western capitals’ afternoon briefings. A senior State Department official, speaking on condition of anonymity to describe internal deliberations, said the gap was “consistent with multiple plausible scenarios,” including pre-war dispersal to small holding sites, in-strike destruction, or relocation by the Revolutionary Guard’s nuclear protection unit. The official said U.S. intelligence had been monitoring the question since early April and was “not surprised, but not satisfied.”

European officials struck a similar tone. “We always assumed there would be a number we could not square. The question is what mechanism gets us to a verified zero over time,” said a senior French official traveling with Foreign Minister Catherine Colonna, who declined to be quoted by name. France, Germany and the United Kingdom have circulated a draft annex that would require Iran to declare all enriched material at any location within 30 days of any framework’s signature, backed by snap-inspection rights at undeclared sites.

For Tehran, the political optics are double-edged. Conservative outlets seized on the report’s catalog of destruction to argue that further concessions amounted to surrender; reformist commentators pointed to the IAEA’s finding of no clandestine work since the ceasefire as evidence that Iran was negotiating in good faith. President Masoud Pezeshkian, addressing parliament on Wednesday afternoon, called the report “a record of what was done to us and what we have nothing to hide from,” and said the government would continue to cooperate “to the limit of our sovereignty, and not beyond.” Reformist lawmakers applauded; about two dozen conservative members walked out.

Markets, which had ticked lower at the open on concern that the report would derail the talks, recovered through the European session as traders concluded that the findings, while uncomfortable, did not break the diplomatic track. Brent crude was down 40 cents at $95.70 a barrel in late London trading. “The report tells you the war achieved its narrow military aim and that the verification problem is now a negotiation, not a confrontation,” said John Reilly, an analyst at Citi. “Both of those are, on balance, supportive for prices going lower into the summer.”

Inside the Palais Coburg, technical working groups were scheduled to meet through the evening on three threads: a verification protocol for declared sites, a chain-of-custody mechanism for any recovered material, and a confidence-building roadmap for the Isfahan facility. Diplomats said a fuller IAEA report was expected within ten days, and that a draft framework text could be ready for ministerial review by the tentatively planned Doha round in mid-May.

Grossi, asked late Wednesday whether he believed an agreement could be reached, paused before answering. “I believe an agreement is necessary,” he said. “Whether it is reachable is a question for the ministers in this building, not for the inspectors in mine.” Officials said additional working sessions would be announced as drafting work progressed.