An advance team of International Atomic Energy Agency inspectors arrived in Tehran on Sunday and, within hours of landing, certified that surveillance cameras at the Natanz fuel enrichment plant and the Tehran Research Reactor had been reactivated, marking the first operational step of the inspections accord that Iran and the agency finalized in Geneva on April 28.

The eleven-member team, led by Deputy Director General Massimo Aparo of the IAEA’s Department of Safeguards, was met at Imam Khomeini International Airport by Behrouz Kamalvandi, spokesman for the Atomic Energy Organization of Iran, in what Iranian state television described as a “businesslike” reception. By late afternoon Tehran time, technicians in Vienna confirmed that real-time imagery and seal-monitoring data had begun flowing from cameras at two of the four sites covered under the accord — Natanz and the research reactor — with the remaining two sites scheduled for activation over the next forty-eight hours.

The arrival is the most visible step yet in the post-war diplomatic architecture assembled since the Islamabad ceasefire took effect on April 15, and it converts a paper agreement into a functioning monitoring regime that European and Gulf negotiators have argued is essential to unlocking the first tranche of sanctions relief sketched in the Geneva draft.

“What happened today is what diplomacy is supposed to look like when it works — quiet, technical, and visible only to the people who needed to see it,” IAEA Director General Rafael Grossi told reporters at the agency’s Vienna headquarters in a Sunday evening statement. “The cameras are live. The seals are in place. The inspectors are on the ground. We will report what we find, without commentary and without delay.”

The inspections cover four nuclear sites that were not struck during the war: Natanz, the Tehran Research Reactor, the Esfahan uranium conversion facility and the Bushehr power reactor. The partially destroyed Fordow enrichment plant and the Arak heavy-water complex, both of which were hit in the final Israeli strikes of April 13 and 14, remain the subject of a separate technical working group that is expected to convene in Vienna later in May. Grossi said the agency would not characterize the condition of those sites publicly until the working group reported.

Iranian officials sought to frame Sunday’s arrival as a sovereign decision rather than an external imposition. In a statement issued from the foreign ministry, spokesman Esmaeil Baghaei said the resumption of monitoring “reflects Iran’s longstanding commitment to the Nuclear Non-Proliferation Treaty and to peaceful nuclear cooperation, on terms consistent with the country’s national interests.” Baghaei made no reference to the Geneva sanctions roadmap and pointedly noted that Iran’s enrichment program “continues within the parameters set by the Supreme National Security Council.”

The advance team’s arrival had been negotiated down to the hour over the final days of the previous week. A senior European diplomat involved in the talks, speaking on condition of anonymity, said the Iranian side had pressed for a symbolic delay until after a planned Majlis session on Monday, while the agency had insisted on activation before the May 6 reconstruction conference in Marseille so that donor governments could cite operational monitoring in their pledge calculations. A compromise was reached late Friday under which the team would land on Sunday morning and cameras at the two most politically sensitive sites would come online the same day.

In Washington, the State Department welcomed the development in a measured statement that emphasized the conditional nature of the broader framework. “The United States has consistently said that verified compliance is the foundation on which any sanctions sequencing will rest,” spokesperson Matthew Miller said. “Today is a step. It is not, by itself, the substance of an agreement.” A senior administration official, briefing reporters on the condition of anonymity, said the White House would await at least two weekly IAEA reports before convening the interagency review that would precede any first-tranche action.

Israeli officials offered a sharper tone. In a statement from his office, Prime Minister Benjamin Netanyahu, whose coalition has fractured over the Islamabad framework, said Israel would assess the inspections regime “on the basis of what it actually verifies, not on the photographs of arrivals at Tehran’s airport.” A senior Israeli official, speaking on condition of anonymity, said Jerusalem had received private assurances from Washington that any sanctions tranche would be contingent on monitoring data being shared with Israeli technical authorities through an established U.S.-Israel channel.

“The inspections are necessary but they are not sufficient,” said Ariane Tabatabai, a senior fellow at the German Marshall Fund who has written extensively on Iran’s nuclear program. “What the IAEA can verify with cameras at Natanz is whether the centrifuges that were spinning before the war are spinning now. What it cannot verify, without far more intrusive access, is whether a parallel program has been reconstituted at sites the agency does not visit. That is the conversation that has to come next.”

The Marseille conference, which opens Wednesday with French President Emmanuel Macron and the foreign ministers of nineteen countries, is expected to formalize donor pledges for Iranian, Iraqi and Yemeni reconstruction totaling roughly $48 billion over three years, according to a draft communiqué that circulated among European capitals on Friday. European officials said the inspections accord had eased internal opposition within the European Union to releasing the second tranche of the EU’s Neighborhood Instrument funds, with Germany and the Netherlands dropping objections after Grossi’s Saturday phone briefing to capitals.

Saudi Foreign Minister Prince Faisal bin Farhan, in a brief statement issued from Riyadh, said the kingdom welcomed the resumption of monitoring as “an indispensable element of the regional security architecture we are building together,” and confirmed that Saudi Arabia would send Energy Minister Prince Abdulaziz bin Salman to Marseille alongside the foreign minister, a level of representation that European hosts said reflected Riyadh’s commitment to anchoring reconstruction financing in long-term energy stability.

The Geneva framework calls for the first sanctions tranche — covering aviation insurance, the unfreezing of roughly $3.4 billion in Iranian assets held in South Korean and Japanese banks, and a humanitarian clearing mechanism administered by Switzerland — to take effect within thirty days of signature, contingent on the inspections regime being judged operational by the IAEA. Sunday’s activation begins the technical clock on that assessment, though the formal framework itself remains unsigned pending the Iranian Supreme National Security Council’s response, which Iranian officials have said is expected in the coming days.

Inspectors are scheduled to conduct their first physical walkthrough at Natanz on Monday morning. Grossi said the agency would issue its first situation report by the end of the week, with weekly updates to follow until the working group on Fordow and Arak completed its assessment. Officials said additional steps on access to non-declared sites would be addressed in subsequent technical annexes.