- Heaviest ever. CSIS analysts found more road and construction activity at Iran’s Pickaxe Mountain site in 2026 than at any point in the facility’s recorded history, concentrated since January.
- IAEA locked out. The International Atomic Energy Agency has requested access and information about the facility since it was first identified. Iran has never responded, and inspectors have never set foot inside.
- Natanz proximity. The site sits 2 kilometres south of the Natanz uranium enrichment complex, buried 80–100 metres deep in granite, with U-shaped tunnel portals designed to defeat direct missile strikes.
What the Imagery Shows
A satellite imagery analysis published on September 9 by the Center for Strategic and International Studies — authored by Joseph Rodgers, Douglas Comstock, and Joseph S. Bermudez Jr. — identified a third and distinct construction phase at Pickaxe Mountain that began in January 2026 and shows no sign of slowing. The report describes “more road activity at Pickaxe Mountain in 2026 than at any point in the site’s history,” with specific construction concentrated on raising and hardening the portal access points, paving internal road networks, reinforcing areas surrounding the access zones, and removing excavation spoil from the surface.
The pattern, CSIS analysts note, reflects a shift from the active excavation of earlier phases toward “probable internal construction and continued exterior reinforcement” — suggesting the physical shell of the facility is nearing completion even as its interior fit-out proceeds. The facility’s U-shaped tunnel portals are explicitly engineered to prevent direct strikes from penetrating the complex, the analysis states.
IAEA Access and Iran’s Response
IAEA Director General Rafael Grossi acknowledged the activity in a September 10 interview, confirming the agency has “requested information about Pickaxe Mountain and access to the facility.” Iran has never responded to those requests. As CSIS reports, inspectors have never been permitted inside the site. The absence of an IAEA presence means the intended purpose of the underground complex — whether enrichment infrastructure, weapons-related research, or hardened command capability — remains unconfirmed.
The IAEA’s ability to verify Iran’s nuclear activities is already constrained. Tehran revoked advanced access protocols in 2021 and has operated outside the Additional Protocol’s inspections framework for much of the subsequent period. Pickaxe Mountain represents a category of facility entirely outside that monitoring system: one the agency knows exists and has asked about, but where it has obtained no access at all.
Strategic Context
The construction surge at Pickaxe Mountain coincides with the most intensive period of the US-Iran military confrontation over Hormuz transit, which has dominated the region since early 2026. The facility’s proximity to Natanz — itself a target in Israel’s Operation Rising Lion strikes in 2025 — and its depth in hardened granite have drawn attention from US planners weighing options for any expanded military action against Iran’s nuclear infrastructure. The CSIS analysis notes that the facility is “not yet capable of enrichment work, if that is the intended purpose,” but cautions that the pace of construction implies operational capability could follow within a horizon that remains uncertain.
Iran has simultaneously advanced hardening work at other declared and undeclared nuclear sites, part of a broader dispersal and survivability strategy analysts say was accelerated after the Natanz strikes. The widening of Pickaxe Mountain’s road network and portal reinforcement, visible even through commercial satellite imagery, underscores how openly Iran has proceeded with activities it knows are being observed — a posture consistent with deterrence signaling as much as operational preparation. The site’s expansion intersects directly with ongoing diplomatic calculations about the viability of any negotiated end to the Hormuz standoff.