Iran Makes Progress on Constructing Underground Nuclear Site

Latest Developments

A March 25 report found that Iran continues to make progress in constructing a deeply buried nuclear site near Natanz. The report by the Institute for Science and International Security discovered — based on analysis of satellite imagery — that Iran has completed construction of tunnels related to the site and is working on underground rooms that could hold enrichment halls. The site may be invulnerable to military strikes, allowing Tehran to successfully produce weapons-grade uranium for a nuclear weapon using material diverted from other facilities.

Expert Analysis

“This Iranian nuclear weapons-making facility could be impervious to Israeli and perhaps even American bombs. The time is quickly running out, as Iran moves into a zone of nuclear immunity, to deny the regime permanent use of this deadly site.” — Mark Dubowitz, FDD CEO

“If Tehran is allowed to complete this facility and move its enrichment infrastructure inside, we will enter a new and potentially irreversible era of the Iranian nuclear threat. Completion of this facility must be added to the list of red lines for the United States and its allies.” — Richard Goldberg, FDD Senior Advisor

“Iran has successfully distracted the West from focusing on ongoing construction at the Natanz facility, which could allow the Tehran regime to complete a dash to nuclear weapons. Washington must prevent Iran from acquiring a nuclear deterrent and permanently changing the game in the Middle East.” — Andrea Stricker, FDD Research Fellow and Deputy Director of FDD’s Nonproliferation and Biodefense Program

Deeply Buried Site

Iran claimed it is constructing a new centrifuge assembly facility in the mountains near its Natanz uranium enrichment complex to replace a similar, above-ground facility that Israel likely destroyed in 2020. The Institute for Science and International Security assessed in 2022 that the new site could be nearly 150 meters deep — deeper than Iran’s Fordow enrichment plant — and that Tehran might opt to build a secret enrichment plant there.

Failure to Declare Nuclear Facilities

Iran has long failed to declare to the International Atomic Energy Agency (IAEA) when it has made a decision to construct enrichment facilities. Tehran has also not provided the IAEA with design information, as required by Modified Code 3.1 of its safeguards agreement. Tehran previously constructed the Natanz, Natanz pilot, and Fordow enrichment plants in secret, raising concern that it will not declare a new, similar facility or allow the IAEA to implement safeguards.

Related Analysis

“Preventing an Iranian Nuclear Weapons Remains Israel’s Top Priority,” by Jacob Nagel and Mark Dubowitz

“Iran Failed to Declare New Nuclear Facility, IAEA Reports,” FDD Flash Brief

“Iran Must Notify About New Enrichment Facilities,” by Andrea Stricker