REPORT: Iran Opens Its Nuclear Sites to the IAEA — The West Holds Its Breath

Introduction: The Secret Letter That Changed Everything

Witkoff's revelation before Congress

On June 18, 2026, in a closed-door Capitol briefing room, Steve Witkoff, President Trump's special envoy, revealed to congressional leaders and members of the national security committees the existence of a document that had not yet been made public: a letter addressed by Tehran to IAEA Director General Rafael Mariano Grossi. This letter, a discreet annex to the memorandum of understanding signed between Washington and Tehran, contains a formal Iranian invitation to the International Atomic Energy Agency to inspect its nuclear sites. It goes further still: it would allow Grossi to bring American nuclear inspectors into Iranian facilities.

The news was confirmed by anonymous sources with knowledge of the confidential session, cited by the Associated Press. Iran was about to — for the first time since the start of American-Israeli strikes in June 2025 — reopen its doors to the international nuclear monitoring community. But the conditional is warranted: the invitation has been drafted; it has not yet been executed. Inspectors have not yet crossed Iranian checkpoints. The promise is on paper. Reality will be measured in the field.

A year of nuclear radio silence

To grasp the significance of this letter, one must appreciate the scale of the void it is meant to fill. Since the Israeli-American strikes of June 2025 on Iranian nuclear facilities — the sites of Fordow, Natanz, and Isfahan — the IAEA had been denied access to those installations. Iran suspended all cooperation with the UN agency, initially in protest at the IAEA's failure to condemn Israel and the United States, then formalizing that suspension via a law signed by President Pezeshkian on July 2, 2025. For nearly a year, Iran's nuclear program — or what remained of it after the strikes — had been developing in total darkness, beyond the reach of international monitoring.

This void is one of the most severe nuclear non-proliferation crises in recent history. The IAEA itself described it as a situation of "absolute urgency." At the last available assessments before the strikes, in June 2025, Iran possessed 440.9 kilograms of uranium enriched to 60% — just below the 90% required for weapons-grade material. If enriched to 90%, that quantity would be sufficient to build 10 nuclear bombs according to IAEA criteria. Nobody knows with certainty where that uranium is today.

The Chronology of a Year of Nuclear Chaos

The strikes and the collapse of inspections

The chain of events that led to the June 2026 letter began on the night of June 12–13, 2025, when Israel launched a military operation against several Iranian nuclear facilities. Attacks took place between June 13 and 24, 2025. On June 22, 2025, the United States joined the operation and struck three Iranian nuclear sites. The IAEA immediately halted its verification activities in Iran and withdrew all its inspectors from the country on security grounds.

The seven declared nuclear installations the IAEA considers affected by the military strikes are: the Fordow Fuel Enrichment Plant (FFEP), the Fuel Enrichment Plant (FEP), the Pilot Fuel Enrichment Plant (PFEP), the UCF, the FMP, the FPFP, and the EUPP. The heavy-water research reactor at Khondab, then under construction, was also hit. Furthermore, Iran informed the IAEA in February 2026 that a site whose precise location the agency did not yet know — designated IFEP — had also been "subjected" to military attacks.

Attempts to restart the dialogue

In September 2025, Iran and the IAEA concluded an agreement intended to allow the resumption of inspections across all Iranian nuclear sites, including the bombed ones. But by September 20, 2025, Iran had suspended that cooperation in retaliation for an IAEA resolution demanding full access — a resolution pushed by the United Kingdom, France, and Germany, which had also activated the UN sanctions snapback mechanism under what remained of the JCPOA. This cycle of agreements followed by withdrawals characterized the entire period from September 2025 through June 2026.

In January 2026, IAEA chief Grossi had declared at the World Economic Forum in Davos that "the impasse with Iran over the accounting of its highly enriched uranium stockpile and inspections of bombed nuclear facilities cannot go on indefinitely." He confirmed that the IAEA had inspected the 13 unbombed facilities at least once since the strikes — but none of the 8 affected installations. Since February 28, 2026, the IAEA had officially "ceased conducting verification activities in Iran in accordance with the NPT safeguards agreement."

The Missing Uranium: Where Is Iran's Stockpile?

The mystery of the 440 kilograms

The question that has obsessed non-proliferation experts since June 2025 is simple to formulate and terrifying in its implications: where are the 440.9 kilograms of uranium enriched to 60% that Iran possessed according to the IAEA before the strikes? Director General Grossi estimated, in public assessments, that the bulk of this uranium probably remains in the Isfahan underground complex — struck during the attacks. But "probably" is not certainty, and Grossi indicated that the IAEA is also seeking access to the sites of Natanz and Fordow, where nuclear material is present.

The Foundation for Defense of Democracies (FDD) report of June 9, 2026 — the last comprehensive public analysis of IAEA reports before the memorandum was signed — painted a bleak picture: the agency is unable to verify the suspension of uranium enrichment, plutonium reprocessing, and heavy water production in Iran. It cannot report on enriched uranium stockpiles, their location, size, or chemical composition. Several candidate sites where material could be "entombed" — including underground tunnels near Natanz and in the Pickaxe Mountain area — are not mentioned in official reports.

The question of secret, undeclared sites

One of the most troubling dimensions of the Iranian nuclear crisis is the possibility of undeclared enrichment sites. Iran has, in the past, built clandestine enrichment facilities that the IAEA only discovered thanks to external intelligence — the Fordow site itself was revealed by Western intelligence services in 2009. Whether Iran has secret enrichment capabilities, sheltered from military strikes and inspections, is a fundamentally open question. No one can answer it with certainty.

This is precisely what makes the Iranian invitation to the IAEA so critical — and potentially so insufficient. If Iran only opens its declared sites while maintaining clandestine capabilities, inspections would merely create an illusion of transparency. The memorandum clause asking Iran to "begin the work of identifying and revealing the locations of its enriched material" is an implicit acknowledgment of this anxiety: Washington wants to know not only what is in the known sites, but what may be elsewhere.

Grossi: The Agency Chief Under Maximum Pressure

A man caught between two fires

Rafael Mariano Grossi, IAEA Director General since 2019, is the man at the center of this nuclear crisis. He has publicly expressed, in interviews and reports, growing frustration with Iranian opacity. He has insisted on the need for access with "absolute urgency" to the bombed sites. He called the situation "unacceptable." And he has maintained a thread of dialogue with Tehran even during the most tense periods.

Grossi navigates a diplomatically minimal space: on one side, the major Western powers — the United States, the UK, France, Germany — demanding immediate and full access to all Iranian sites. On the other, Iran, which uses inspection access as diplomatic currency, and IAEA board members like China and Russia who moderate Western pressure. His room for maneuver is narrow. But his institutional credibility remains a precious asset for any future negotiation.

What "inspecting" a bombed site actually means

A technical but absolutely crucial dimension of this crisis is the question of what it means to "inspect" nuclear sites that have undergone massive military strikes. At Natanz, Fordow, and Isfahan, physical structures were partially or totally destroyed. Enrichment centrifuges — extremely sophisticated and fragile machines — may have been destroyed, but the fissile material they contained could have been dispersed, moved, or recovered. Inspection work is not a simple site visit. It is a nuclear forensics operation that can take months, in environments potentially hazardous to inspectors' health and safety.

The Iranian invitation to the IAEA is therefore also a considerable logistical and technical challenge. Who finances these inspections in damaged sites? What equipment is needed to measure and locate dispersed radioactive material? How do inspectors protect themselves from radiological risks in makeshift conditions? These practical questions were not resolved in the memorandum. They will need to be in the 60 days of negotiations that follow.

International Reactions: Measured Hope and Persistent Skepticism

Washington: diplomatic victory or act of faith?

The Trump administration presented the Iranian letter to the IAEA and the ceasefire agreement as a major diplomatic victory. Witkoff summarized the American logic in his now-famous formulation: "We do not trust words. We trust acts and conduct." The inspection invitation is an act. Not yet conduct — conduct is measured over time, through repeated and verifiable actions. Washington seems to understand that the final deal in 60 days will be the real test of truth.

But the legitimate critique from the hard Republican opposition is this: how do we know whether the Iranian invitation is sincere or tactical? Iran already signed inspection agreements with the IAEA in September 2025 — and renounced them three weeks later. What guarantees that the June 2026 letter will not also be withdrawn if political conditions change? The honest answer is: nothing, for now. Only the formal guarantees of the memorandum.

Europe: between relief and concern over the details

The three European countries party to the JCPOA oversight mechanism — the UK, France, and Germany — are welcoming the deal with cautious relief. In a statement published by the British government on June 10, 2026 — a few days before the signing — His Majesty's government had once again condemned Iranian delays in IAEA inspections, calling Iran's refusal "unacceptable."

The Europeans are in a delicate position: they had activated the UN sanctions snapback mechanism against Iran in October 2025, triggering the breakdown of the September 2025 IAEA-Iran agreement. Now that Washington is negotiating directly with Tehran, the Europeans find themselves marginalized in a process that directly affects their security — through the risks of nuclear proliferation and energy flows. How Europe will integrate into the final 60-day negotiations is an open political variable.

China's Role: Tehran's Silent Partner

Beijing, the Iranian regime's economic guarantor

Throughout the conflict period and under maximum sanctions, China was Iran's only major oil buyer. Tehran earned an estimated $45 billion in oil revenues the previous year — almost exclusively thanks to Beijing. Without this Chinese economic support, the Iranian regime would likely have faced an even more severe financial crisis. China thus played the role of a strategic lifeline for Iran, allowing it to weather Western sanctions and continue funding its regional proxies.

This silent economic partnership has direct implications for nuclear inspections. China has consistently moderated Western pressure within the IAEA Board of Governors and the UN Security Council. It has vetoed or hedged the most demanding resolutions against Iran. Its influence on Iran's decision whether or not to accept inspections is real, even if exercised behind closed doors. Beijing officially welcomed the American-Iranian deal — a position experts interpret as a calculation to preserve access to Iranian oil and maintain its influence over Tehran in the new post-deal configuration.

Sino-American rivalry and the Iranian nuclear file

There is a paradox in China's position on Iranian nuclear matters. On one hand, China does not want to see Iran acquire nuclear weapons — it would create regional instability harmful to its economic interests and could trigger a chain of nuclear proliferation in the region (Saudi Arabia, Turkey, and the UAE have all expressed interest in nuclear capabilities if Iran were to get the bomb). On the other hand, China does not want the United States to win too complete a diplomatic victory over Iran, which would consolidate American dominance in a region where Beijing is seeking to expand its influence.

This Chinese ambivalence translates into nominal support for nuclear verification but real resistance to the intrusive verification mechanisms that would give the IAEA and the United States a comprehensive view of the Iranian nuclear program. The demand for full access, including to military sites potentially linked to a weapons program, is as much a Chinese red line as an Iranian one. It will be at the heart of the 60-day negotiations.

The Bombed Sites: What We Know and What We Don't

Natanz, Fordow, Isfahan: the state of knowledge

The IAEA has partial information on the state of the bombed sites, based on pre-strike assessments and publicly available satellite imagery. At Natanz, the main uranium enrichment site, strikes targeted both surface installations and underground structures. The depth of the enrichment tunnels — some tens of meters underground — may have protected some equipment from penetrating bombs. Unconfirmed reports suggest centrifuges may have been moved to backup sites before or during the strikes.

At Fordow, the enrichment site carved into a mountain in central Iran, structural damage is estimated as more extensive, but again, the site's depth raises questions about the survival of the deepest equipment. At Isfahan, the uranium processing complex that likely held the majority of the 440-kilogram enriched uranium stockpile, damage to surface buildings is documented, but the condition of underground tunnels and bunkers remains unknown. Grossi indicated that according to his assessments, the majority of the enriched uranium stockpile was probably still at Isfahan at the time of the assessments.

IFEP: the mystery of the unknown site

One of the most troubling aspects of the crisis is the site designated IFEP — a new enrichment facility that Iran had notified the IAEA of on June 12, 2025, the day before the first Israeli strikes. The IAEA had immediately requested access for an inspection — and had to cancel inspection plans due to the start of military strikes on June 13. Since then, Iran informed the IAEA in February 2026 that this IFEP had also been "subjected" to military attacks. But the IAEA still does not know the precise location of this site and therefore cannot verify its condition.

The existence of IFEP reveals something fundamental about Iran's nuclear strategy: the Iranians were still building new enrichment facilities right up to the last days before the strikes. This suggests either that the proliferation program was more advanced than the IAEA estimated, or that Iran was seeking to prepare for escalation by diversifying its capabilities. In either case, an invitation to inspect known sites is insufficient if unknown sites still exist.

The Proposed Verification Mechanism: Can It Work?

The structure of the announced inspection

According to available information on the memorandum and the side letter, the proposed verification mechanism includes several elements. First, Iran's formal invitation to the IAEA to access its nuclear sites. Second, a specific clause allowing the IAEA to include American nuclear inspectors on its teams — a significant departure from usual practice. Third, an Iranian commitment to "begin the work of identifying and revealing the locations" of its enriched material.

This last point is particularly important: Iran does not commit to immediately and exhaustively declaring all its enriched uranium locations. It commits to "beginning the work" of identification. That is a deliberately vague formulation that leaves Tehran room for maneuver. For Witkoff, it is sufficient because "we do not trust words, we trust acts." For critics, it is a potential escape route for Iran if it wants to slow or undermine the process.

The precedents that inspire mistrust

The history of nuclear verification agreements with Iran is a long series of promises followed by withdrawals. The 2015 JCPOA established what its defenders called "the most robust inspection regime ever negotiated" — with 24-hour access, additional protocols, and permanent surveillance cameras. In 2018, Trump tore it up unilaterally. In retaliation, Iran progressively reduced its commitments, increased its enrichment, and ultimately suspended all IAEA cooperation in 2025.

The September 2025 agreement meant to restart inspections lasted three weeks before Tehran renounced it. Every time Iran came under pressure — IAEA resolutions, European sanctions snapbacks — it used inspections as bargaining chips, threatening to suspend cooperation to extract concessions. This behavioral pattern must be factored into any assessment of the June 2026 invitation's solidity. The Iranian letter to Grossi is not a spontaneous act of good faith — it is a strategic choice conditioned by immediate economic interests (sanctions relief, reopening of oil markets).

The Challenge of Dismantling Enrichment: What the Deal Really Demands

The centrifuge question

The agreement asks Iran to "dilute its stockpile of highly enriched uranium" under IAEA supervision. This "dilution" — the process of reducing the concentration of enriched uranium from 60% to 3.67% or below, the level used in civilian nuclear reactors — is a technical operation that takes time and requires specific equipment. It is reversible: diluted uranium can be re-enriched if Iran has the necessary centrifuges.

The real question is therefore the centrifuges. Iran possessed, before the strikes, thousands of installed centrifuges — a mix of relatively basic IR-1 models and far more advanced and efficient IR-6 and IR-8 models. How many were destroyed? How many survived in underground tunnels? How many were relocated before or during the strikes? Without verified answers to these questions, diluting the current uranium stockpile is a superficial measure if Iran can quickly re-enrich once inspections ease.

Permanence versus reversibility

The real test of the Iranian agreement will be its permanence. In the 2015 JCPOA, some restrictions were "permanent" (in theory) — such as the prohibition on weapons manufacturing — while others were temporary (10 to 25 years depending on the provisions). The current agreement, based on a 60-day memorandum pending a final deal, is structurally only the opening of the negotiation. Questions of permanence, reversibility, and long-term verification will be at the heart of the "big deal" the two parties are meant to finalize by August 2026.

The Iranian Parliament and the Supreme Leader will have their say. Ayatollah Mojtaba gave his blessing to direct negotiations with the United States — a remarkable evolution from the regime's traditional position of refusing any direct contact with "the Great Satan." But this opening has limits. It is difficult to imagine the Iranian regime accepting provisions that completely eliminate all enrichment capacity — that is a national sovereignty red line that even Iranian moderates cannot cross politically.

The IAEA at Its Limits: An Agency Exhausted by an Unprecedented Crisis

The agency's institutional limitations

The IAEA is an international agency with limited resources, operating by consensus among members with often divergent interests. It has demonstrated, in the Iranian case, the structural limits of its mandate: it can inspect what it is allowed to inspect, report what it observes, and flag non-compliance. But it cannot compel a state to cooperate. It cannot force open a door behind which a nuclear weapons program may be hiding. It has no military force or coercive power.

Its credibility depends entirely on the good faith of member states and the willingness of great powers to give it the political and financial means to fulfill its mandate. When China and Russia shield Iran at the UN Security Council, when Iran itself expels its inspectors, the IAEA is powerless. The June 2026 letter does not change this structural reality. It gives the agency a window of opportunity. It is up to the international community to ensure that window does not close at the first political pressure.

The geopolitical significance of nuclear transparency

There is a profound geopolitical dimension to the stakes of Iranian nuclear inspections. A transparent Iran, open about its nuclear program, is an Iran that accepts operating within the rules of the liberal international order — an order it has contested since its 1979 revolution. An opaque Iran, concealing its nuclear activities from the international community, is an Iran placing itself outside that order, claiming the right to make its own rules and threaten its neighbors without accountability.

Iran's decision to invite the IAEA — even if tactically motivated by the economic benefits of the deal — is therefore a symbolically significant gesture. It does not transform the Iranian regime into a reliable partner of the international order. But it opens the possibility of an engagement that, sustained and reinforced over the long term, could gradually modify the relationship between Iran and the international community. That is a fragile hope. But it is a hope the world must take seriously.

Israel and the 60 Days: The Explosive Variable

Tel Aviv, the great absent from the negotiations

There is one fundamental actor in this nuclear crisis that is not party to the deal: Israel. It was Israel that launched the first strikes on Iranian nuclear facilities. It was Israel that spent a decade conducting targeted assassinations of Iranian nuclear scientists, cyberattacks (Stuxnet), and sabotage operations to delay Tehran's nuclear program. And it is Israel whose official position for years has been that a nuclear Iran represents an existential threat to the Jewish state.

The Netanyahu government has every reason to be skeptical of any deal that leaves Iran with residual nuclear capability, however reduced. JD Vance attacked Israeli criticism of the deal — a clear signal that Washington will not allow Tel Aviv to sabotage the negotiations. But Israel has demonstrated in the past that it is willing to act unilaterally when it considers its vital interests threatened. If Tel Aviv concludes that the deal leaves Iran too close to the bomb, a resumption of Israeli military strikes — within the 60-day negotiating window — is a real possibility.

The catastrophic scenario

The catastrophic 60-day scenario runs as follows: negotiations bog down on technical details about centrifuge dismantlement and access modalities for potential clandestine sites. Israel, convinced Iran is playing for time, resumes air strikes. Iran retaliates by expelling IAEA inspectors and reinstating Strait of Hormuz tolls. Energy markets plunge back into crisis. The deal collapses.

This scenario is not inevitable — but it is possible. To prevent it, Washington will have to maintain constant pressure on Tehran for real and verifiable concessions, while managing Israeli impatience and maintaining the cohesion of a diverse international coalition. That is extraordinarily demanding diplomatic management, in an extraordinarily tight timeframe. The world holds its breath.

The American Intelligence Community: Cautious by Design

What intelligence services actually know

Behind the public statements and diplomatic letters, American intelligence services — CIA, DIA, NSA — maintain a continuously updated assessment of the Iranian nuclear program. These assessments are classified, but certain elements regularly filter through to media and Congress members in briefings. What the intelligence community knows about the current state of the Iranian nuclear program — how many centrifuges are active, where exactly the enriched uranium is, what reconstruction capabilities exist — will largely determine American negotiating positions in the 60-day talks.

Witkoff told Congress that American nuclear inspectors could participate in IAEA missions in Iran. This is an unprecedented provision that would allow Washington to have its own eyes inside Iranian facilities — not as a replacement for international inspectors, but as a complement. This direct American participation in the inspection process would be an additional guarantee of verification quality.

The West's absolute red line

Despite all the nuances and complexities of the negotiation, there is one absolute red line on which the entire Western community — the United States, the UK, France, Germany, Israel — agrees: Iran cannot be permitted to acquire an operational nuclear weapon. This red line cannot be negotiated, conditioned, or deferred. It is absolute. Any agreement that does not credibly and verifiably guarantee this outcome is not a real agreement — it is a deferral of the problem.

That is the standard against which the 60 days of negotiation will be judged. Not Trump's rhetoric, not Iranian communiqués, not market reactions. One simple question: at the end of these 60 days, will Iran be structurally incapable of acquiring a nuclear weapon within a reasonable timeframe? If the answer is yes, with credible verification mechanisms, the deal will have fulfilled its promise. If the answer is no, or if it remains uncertain, the world will be in a dangerous position — with an Iranian nuclear threat less visible but perhaps more advanced than before.

The Regional Players: Who Really Wins in the Witkoff Deal?

Israel: between tactical relief and strategic anguish

For Israel, the nuclear deal that Witkoff is constructing generates deep and legitimate anguish. If 440.9 kilograms of uranium enriched to 60% represents the raw material for ten potential nuclear bombs, then the question of dilution under IAEA supervision is not an administrative formality — it is an existential question. Jerusalem struck three Iranian nuclear sites in 2025. Those strikes slowed the program but did not stop enrichment. The Netanyahu government now demands that any deal include an irreversible verification mechanism: not Iranian promises, not voluntary IAEA invitations, but binding inspections with unlimited access to all declared and undeclared sites.

The tension between Washington and Jerusalem on this file is real. Trump wants a deal that looks like a diplomatic victory before the 2026 midterm elections. Netanyahu wants the irreversible destruction of the enrichment program — nothing less. These two objectives are not incompatible, but they are not naturally aligned either. The sixty days will serve to measure whether Witkoff can hold these two allies together. That is not guaranteed.

Russia and the multipolar context: a deal that troubles Moscow

One crucial element is often forgotten in the analysis of the Witkoff deal: Russia does not want a nuclearlyappeased Iran. Moscow has used Iran as a lever of pressure on the West, as a drone supplier for Ukraine, as a partner in sanctions evasion. An Iran that normalizes its relations with the United States weakens the Moscow-Tehran axis that consolidated after 2022. The Kremlin is watching these negotiations with growing wariness — not because it wants Iran to be nuclearized, but because a diplomatically reintegrated Iran would be far less dependent on Moscow.

This dimension is underreported but fundamental. A solid Iranian nuclear deal would not only be a victory for non-proliferation — it would be a geopolitical rupture in the Russia-Iran-China arc that the Kremlin has labored to build since 2022. That may be why Putin has not officially reacted to the first days of the Witkoff deal — Russian commentators are observing, measuring, searching for the faults. Moscow's silence is rarely a sign of serenity.

Conclusion: The Hour of the Great Test for Nuclear Diplomacy

60 days to change history

The Iranian invitation to the IAEA is a real and significant step. After a year of nuclear radio silence, after months of failed diplomatic negotiations, after terrifying estimates of missing enriched uranium — this letter opens a window that the West cannot afford to let close. IAEA inspectors will have to enter Iran with sufficient means, genuine access, and credible security guarantees. Washington will have to maintain pressure for verifiable concessions. Europe will have to make its voice heard in the final negotiations. And Israel will have to accept — reluctantly — that an imperfect but verifiable deal is preferable to no deal at all.

The world cannot live indefinitely in this in-between

There is an unavoidable geopolitical reality: the world cannot live indefinitely in the current situation, with an Iran whose nuclear program is partially destroyed but whose residual capabilities are unknown, and whose access to international inspections is suspended. That uncertainty is itself destabilizing — for energy markets, for regional security alliances, for the credibility of the global nuclear non-proliferation regime. The 60 days that are beginning represent the historical opportunity to exit this in-between. Perhaps the last one for a long time. The West holds its breath. With good reason.

Primary Sources

Boston Globe — Iran to invite watchdog inspection of nuclear sites: Live updates — June 18, 2026

Qatar News Agency — US President's Envoy: Iran to Invite IAEA to Inspect its Nuclear Facilities — June 19, 2026

Israel National News — Witkoff tells Congress Iran will invite IAEA to inspect nuclear sites — June 18, 2026

Secondary Sources

Foundation for Defense of Democracies — Analysis of IAEA Iran Verification and NPT Safeguards Reports, June 2026 — June 9, 2026

GOV.UK — UK statement: NPT Safeguards Agreement with Iran, IAEA Board of Governors — June 10, 2026

Al Jazeera — UN watchdog, Western nations call on Iran to restart nuclear cooperation — June 8, 2026

WTAQ/Reuters — Standoff with Iran over inspections cannot go on forever, IAEA chief says — January 20, 2026

Ynet News — Witkoff: Iran to Invite IAEA to Monitor Nuclear Sites and Locate Enriched Material — June 18, 2026