Satellite imagery reveals the Iranian regime racing to rebuild and fortify damaged nuclear tunnel complexes in Isfahan and Kuh-e Kolang.
A new analysis from David Albright, president of the Institute for Science and International Security, reveals accelerated reconstruction and clearing operations at key nuclear tunnel sites hit during recent strikes. The findings show that the Iranian regime is urgently working to reopen and fortify sensitive underground facilities in Isfahan and Kuh-e Kolang—sites long tied to its covert nuclear ambitions.
Satellite data indicates unusually intense activity at the entrances of the massive Isfahan tunnel complex, widely believed to store a significant portion of the regime’s 60-percent enriched uranium. Analysts had previously assessed this underground network as a likely host for a secret enrichment facility hidden deep inside the mountain.
Of the three tunnel entrances at Isfahan, two have now been fully cleared of soil and debris. The southern portal remains blocked, but imagery from November 20 shows the northernmost gate reopened, allowing access underground. The extent of internal damage remains unknown, yet frequent vehicle movement around the portal underscores the regime’s push to restore operations. Two zig-zag anti–cruise missile barriers have been erected outside the entrance—an attempt at passive defense that experts say offers only limited protection against future strikes.
The Kuh-e Kolang mountain site, under steady construction since 2020, is also showing rapid progress. Officially described by the regime as a plant for assembling advanced centrifuges, the facility is believed to be large enough to house a full-scale underground enrichment plant. If the regime succeeds in restoring its centrifuge-production capabilities, the site could churn out several thousand centrifuges annually.
Recent satellite imagery shows that the complex has entered the final stages of construction. Security fencing now surrounds the perimeter, while tunnel entrances are being reinforced with added layers of earth—an effort to harden the site against potential military attacks.
Despite the scale of activity, Albright notes that current evidence does not yet confirm the most extreme scenarios, such as a rush to retrieve damaged high-enriched uranium, enrich it to weapons-grade levels in a clandestine facility, and assemble a deployable warhead. Such an effort would require the regime to evade intelligence services, enrich material to weapons purity, and produce a missile-ready nuclear device—steps that still entail significant risk.
However, the regime’s refusal to grant the IAEA access to these locations, combined with its frantic reconstruction efforts, sends what Albright calls a “dangerous signal.” The absence of transparency increases the likelihood of renewed military strikes, particularly as regional tensions rise and the regime continues to defy international monitoring.
With much of Iran’s centrifuge-related infrastructure damaged in earlier attacks, Albright warns that Kuh-e Kolang is now positioned to become the regime’s main hub for any attempt to revive its centrifuge program—from component manufacturing to assembly and possibly enrichment.
Additional satellite images reveal renewed activity at an older tunnel system built in 2007 near the Kuh-e Kolang complex. Entrances appear to be reinforced in a manner that may make them inaccessible, suggesting the Iranian regime is securing or burying sensitive assets inside. An image from June 18, 2025, shows a truck departing the 2007 tunnel area shortly before entrances were visibly buried under earth.
Albright concludes that the only responsible action would be an immediate halt to all activity at both sites and full transparency. Instead, the regime’s continued secrecy and reconstruction efforts raise alarms—and increase the risk of further military confrontation.
