A prominent American research institute specializing in Iran’s nuclear activities has raised concerns this week about an underground site located in Iran’s Zagros Mountains that remains unexamined by international inspectors.
The International Atomic Energy Agency (IAEA) inspectors have not been granted access to this clandestine site, referred to as Pickaxe Mountain.
This heavily secured facility brings into question Iran’s commitment to the memorandum of understanding (MOU) established with the Trump administration. In response, the United States and Israel initiated Operation Epic Fury on February 28, 2026, aimed at undermining Iran’s nuclear and missile infrastructure.
Experts from the Washington-based Institute for Science and International Security (ISIS) suggest that halting operations at Pickaxe Mountain and permitting IAEA inspections would serve as a crucial step to gauge Iran’s readiness to end its longstanding evasive behaviors.
A satellite image provides a view of the tunnel complex at Pickaxe Mountain in Natanz. (Vantor/Handout via Reuters)
Spencer Faragasso, a senior fellow with the group who covers Iran, North Korea, illicit trade, and nuclear issues, wrote on X: “Important update by us at @TheGoodISIS. The ongoing work at Pickaxe Mountain is deeply concerning. This work has continued steadily since at least 2020. In my view, this is a hedge by Iran in case negotiations fail — they will then have a nuclear facility in a late stage of construction. We assessed that Pickaxe is likely large enough to hold an enrichment plant.”
Iran has used facilities at Natanz, Fordow and Isfahan to enrich uranium, the key material for a nuclear weapons program.
Faragasso added, “If Iran is serious about negotiating, it should halt construction at Pickaxe Mountain as a token of good faith. But what can be expected from a regime as brutal and conniving as Iran’s?”
The institute posted a detailed analysis of new satellite imagery from late June 2026 showing continued activity at Pickaxe Mountain.
Vice President JD Vance prior to a meeting between the United States, Iran, Pakistan and Qatar at the Bürgenstock luxury hotel complex overlooking Lake Lucerne, Switzerland, June 21, 2026. (Fabrice Coffrini/Keystone via AP)
The institute wrote that “at Pickaxe Mountain, vehicle activity can be seen on the roads leading to the open set of Western tunnel portals, indicating that construction inside the tunnel complex, as well as hardening of the tunnel entrance, are ongoing. The MOU signed between the United States and Iran requires that Iran maintain the status quo, which should prohibit construction at any nuclear-related facility, including Pickaxe Mountain.”
In late June, the IAEA declined to answer a detailed News Media query on whether it would seek access to the Pickaxe Mountain facility. According to the satellite imagery obtained by the institute, “at Natanz, little activity can be seen. The access points to the below-ground enrichment halls have not been repaired.
“The personnel entrances remain destroyed, and vehicle entrances remain severely damaged. A single vehicle can be seen on the road outside of the Pilot Fuel Enrichment Plant (PFEP), which was destroyed in June 2025 but was later covered by Iran.”
As U.S.-Iran talks opened Sunday in Switzerland, and a dispute over who controls and monitors billions of dollars in potentially unfrozen Iranian assets emerged. (Fabrice Coffrini/Pool via Reuters)
The institute also reported, “As of June 29, 2026, there is no observed activity at Esfahan. The tunnel portals remain backfilled with dirt.” ISIS tracked developments at the Fordow site, buried inside a mountain north of the holy Islamic city of Qom.
“At Fordow, as earlier reported by the Institute, between May 10 and May 18, Iran added passive defensive measures in the form of earthen/rocky mounds and other objects on the roads leading to the tunnel entrances. The alternating placements of the piles/objects are very precise, which creates a series of chicanes, indicating they are not intended as obstructions but rather to prevent rapid ingress and egress by any vehicle toward the tunnels.”
The institute added, “The June 21 Vantor image shows that the objects along the road remain there. The tunnel portals also remain backfilled with dirt” at Fordow.
News Media sent questions to the State Department and the Iranian Mission to the United Nations.