NATANZ, Iran — An International Atomic Energy Agency technical inspection team began its site visit at the Natanz nuclear facility Tuesday morning, with Iran simultaneously filing its first formal post-ceasefire declaration under the inspection framework currently being negotiated in Geneva. The site visit and the parallel declaration mark the most substantial operational interaction between the IAEA and Iran’s nuclear program since the immediate pre-war period.

The Natanz visit, which had been the principal operational focus of pre-visit coordination during the past two weeks, began at approximately 9 a.m. local time with the inspection team arriving at the facility’s main entrance accompanied by senior officials from the Atomic Energy Organization of Iran. The team is scheduled to spend approximately ten hours at the facility, with access to the principal enrichment hall, the underground gallery complex, and the surface-level support infrastructure.

IAEA Director-General Rafael Grossi, who had arrived in Tehran on Monday afternoon, accompanied the inspection team to the facility entrance before departing for a parallel senior-official consultation at the AEOI headquarters in Tehran. A senior IAEA official, in a brief background statement Tuesday morning from the facility entrance, said the visit had begun “on the operational basis that had been pre-coordinated” and that the inspection team’s substantive scope of access had been “fully confirmed” by Iranian counterparts.

The Iranian declaration filed Tuesday morning, transmitted to the IAEA secretariat in Vienna at approximately 10 a.m. Tehran time through the Iranian permanent mission, provides Iran’s first formal accounting of the configuration of its declared nuclear facilities since the immediate pre-war declaration cycle. The declaration’s substantive content covers the Natanz, Fordow, Arak, Isfahan, and Bushehr facilities and addresses the question of facilities that were damaged during the war period and have since been undergoing reconstruction.

A senior AEOI official, in a Tuesday-morning briefing at the organization’s Tehran headquarters, characterized the declaration as “the substantive operational complement” to the technical site visits being conducted this week and indicated that the declaration had been prepared in coordination with the IAEA secretariat through the past two weeks. The official said the declaration’s substantive scope addressed all of the substantive questions that had been raised in the pre-visit working-level consultations.

The declaration’s treatment of the war-damaged facilities is expected to be a focal point of subsequent IAEA review. The substantive question — whether previously declared facilities that have undergone substantial reconstruction should be treated as continuing under their original declarations or as requiring fresh declarations — has been one of the principal pre-talks impasses in the Geneva protocol drafting process. The Iranian declaration’s treatment of this question will substantively inform the protocol drafting team’s substantive work in the May 25 second-round session.

A senior Iranian foreign-ministry official, in a Tuesday-morning briefing for state media, said the declaration’s substantive content represented “Iran’s full operational compliance with the framework that emerged from the April fifteenth ceasefire” and indicated that the declaration’s scope had been “deliberately calibrated to support the post-war framework’s substantive establishment.” The official said the declaration would be supplemented by subsequent declarations as the inspection regime’s protocol drafting progresses.

The Natanz visit’s substantive operational scope, as briefed to reporters Tuesday morning, includes the team’s access to the facility’s principal enrichment hall and to the underground gallery complex that had been at the center of pre-war access disputes. The visit will also include the team’s review of the facility’s enrichment-monitoring equipment configuration and the team’s collection of environmental samples from designated locations within the facility.

A senior nuclear-verification expert at a major U.S. research institution, contacted Tuesday morning for background, said the Natanz visit’s substantive scope was “fully consistent with the framework that had been outlined in the post-war structuring” and represented “a substantively important operational benchmark” for the broader inspection regime’s establishment. The expert noted that the substantive question of subsequent visit frequency and unannounced-visit modalities would shape the regime’s medium-term operational character.

The U.S. State Department, in a Tuesday-morning statement issued from Washington, said the United States “welcomes the substantive operational progress” represented by the Natanz visit and the parallel declaration and indicated that the administration would maintain its substantively constructive engagement with the post-war framework through subsequent protocol drafting and operational implementation. The statement did not commit the United States to specific subsequent steps.

The Israeli foreign ministry, in a parallel Tuesday-morning statement, said Israel was “monitoring the operational developments at Natanz with appropriate attention” and indicated that the Israeli position on the substantive framework would continue to be informed by “the operational content of the substantive verification activities.” The Israeli statement reflected the continued domestic political context of the Likud primary process and the broader post-war coalition dynamics.

Russian and Chinese reactions to the Natanz visit were brief and consistent with their previous post-war framework communications. The Russian foreign ministry characterized the visit as “an appropriate operational step” and indicated Russia’s continued support for the framework’s substantive establishment. The Chinese foreign ministry characterized the visit as “consistent with the framework’s substantive direction” and indicated continued Chinese support for the IAEA’s substantive role.

The Fordow site visit scheduled for Wednesday morning is expected to be the next operationally significant element of the Grossi visit’s substantive program. Fordow had been at the center of pre-war IAEA inspection access disputes and had been subject to substantially reduced IAEA access since 2023. The Wednesday visit will be the first substantially full-access IAEA visit to Fordow in more than two years.

A senior IAEA official, in a Tuesday-afternoon background briefing, said the Fordow visit’s pre-coordination had been “more substantively detailed” than the Natanz pre-coordination given the longer access gap at Fordow. The official said the substantive scope of the Fordow visit had been “fully agreed” with Iranian counterparts and that the visit would proceed on the planned operational schedule.

The Grossi visit will conclude with a Thursday-afternoon joint press appearance at the Iranian Foreign Ministry, with Grossi expected to deliver a public assessment of the visit’s substantive results before departing for Vienna Friday morning. The substantive assessment will inform the Geneva protocol drafting team’s substantive work in the second-round session beginning May 25.