Iran has a previously unknown underground facility linked to its nuclear program, a new report by experts from the Washington-based Institute for Science and International Security (ISIS) said.

The report said the facility is located in Natanz, near the uranium enrichment nuclear complex. According to experts, the facility is likely related to uranium enrichment for possible use in the production of nuclear weapons.

“The Institute has identified a separately enclosed, partially below-ground, bunkered building at the Natanz Nuclear Complex that was likely intended to serve as uranium hexafluoride (UF6) storage facility to support large-scale uranium enrichment at the Natanz Fuel Enrichment Plant.  The bunkered structure was constructed between 2010 and 2017, with the bulk of construction occurring between 2015 and 2017,” the report said.

The study noted that the facility was not damaged during the US-Israeli strikes on Iranian nuclear facilities in June last year, nor during the current military campaign against Iran.

“The facility does not appear to have been targeted in the military actions of either 2025 or 2026.  Since the June 2025 war, no vehicle activity has been observed at the facility in available satellite imagery,” the experts added.

In their opinion, the information about the existence of a secret facility raises new concerns about whether Iran’s nuclear capabilities were destroyed during two US and Israeli military operations in 2025 and 2026.