A previously undisclosed arrangement between Iran and the International Atomic Energy Agency could pave the way for renewed inspections of Tehran’s nuclear facilities, according to revelations made Thursday by President Donald Trump’s special envoy, Steve Witkoff, during a classified briefing with congressional leaders.

Witkoff told lawmakers that Iran has agreed to provide the United Nations nuclear watchdog with access to its atomic infrastructure and will assist inspectors in locating and identifying its stockpiles of enriched nuclear material, according to an Associated Press report citing two people familiar with the closed-door session.

The briefing was attended by senior members of Congress and lawmakers responsible for overseeing national security matters. During the presentation, Witkoff reportedly emphasized that the memorandum of understanding recently reached between Washington and Tehran contains no secret side agreements. However, he disclosed that a separate letter had been negotiated between Iran and the International Atomic Energy Agency to establish procedures for inspections.

According to the report, neither the existence of that supplemental document nor Iran’s invitation to inspectors had been publicly disclosed before Witkoff discussed them during the briefing. He further explained that a formal communication sent to IAEA Director-General Rafael Grossi specifically authorizes the inclusion of American nuclear experts among the inspection teams entering Iran.

Although joint American and Israeli military operations last June inflicted extensive damage on Iran’s key enrichment facilities, intelligence officials believe that significant quantities of enriched uranium survived the strikes, including material enriched to levels approaching weapons-grade purity.

Iran has thus far declined to tell the IAEA where that material is currently being stored and has refused to grant inspectors access to evaluate conditions at the damaged sites.

An agreement reached between Tehran and the IAEA last September to restart inspections and verify uranium inventories has since collapsed. Iranian officials declared the arrangement void after Britain, France, and Germany moved to restore United Nations sanctions that had been lifted under the 2015 nuclear accord.

Grossi recently stated that he believes most of Iran’s highly enriched uranium remains at the Isfahan nuclear facility, which was among the sites targeted during last year’s strikes.

The IAEA chief also noted that inspectors are seeking renewed access to the nuclear installations at Natanz and Fordow, where additional nuclear materials are believed to remain.