Satellite Images Show New Construction at Secret Iranian Tunnel Complex Near Natanz

Recent satellite imagery shows new construction activity at a secret Iranian tunnel complex near the Natanz nuclear facility, according to the Washington-based Institute for Science and International Security.

The group said Thursday that there is still no clear sign Iran has begun repairing major damage at its main nuclear facilities following US and Israeli strikes. At Natanz, the underground enrichment halls remain inaccessible, with damaged entrances, destroyed power systems, and displaced HVAC equipment still unrepaired.

Activity at Pickaxe Mountain

The institute said satellite images from late June show recent vehicle movement and construction work at the Natanz-area site known as Pickaxe Mountain, or Kuh-e Kolang Gaz La. Workers appear to be reinforcing tunnel entrances at the underground complex, which is built into a mountain near the main Natanz facility.

Experts have said the site has likely been under construction since 2020. Its exact purpose remains unclear, and the International Atomic Energy Agency has never been granted access to inspect it.

The institute reported persistent activity at the site since April, when a ceasefire was declared in the US-Israeli war with Iran. It said Iran has partially filled some tunnel portals, blocking vehicle access, while a smaller tunnel complex within the perimeter has been sealed. The contents of those sealed tunnels are unknown, but the institute said they could include enriched uranium.

Most of the Pickaxe Mountain facility does not yet appear to be operational. Still, the institute argued that any construction there violates the US-Iran memorandum of understanding, which requires Tehran to maintain the status quo of its nuclear program during negotiations.

Fordo and Isfahan Remain Blocked

The watchdog said there has been no recent observable activity at the Fordo uranium enrichment plant or the Isfahan nuclear complex. Tunnel entrances at both sites remain blocked with earth after suffering severe damage during the 12-day war between Israel and Iran in June 2025.

At Fordo, the institute said Iran added earthen and rocky mounds near tunnel entrances in May, possibly as defensive measures to prevent a military operation from entering the facility and seizing uranium stockpiles.

At Isfahan, where most of Iran’s 440-kilogram stockpile of uranium enriched to 60 percent is believed by the IAEA to be stored, the institute said there was no observed activity and that tunnel entrances remain blocked.

Iran Rebuilding Military Sites

Beyond its nuclear sites, Iran has reportedly moved quickly to repair damaged military infrastructure after the war. Reports say Tehran has rebuilt entrances to 50 of 69 tunnels at 18 underground missile facilities across the country.

Iran has also repaired access roads and other key areas at those bases. Experts cited in earlier reporting said Iran may still possess around 1,000 ballistic missiles, many of them stored in underground facilities.

The US and Israel launched strikes against Iran to target its nuclear and ballistic missile programs. A truce began on April 8, and Washington and Tehran are now engaged in talks based on a memorandum reached last month. Israel is not part of the agreement and has criticized it for failing to force real concessions from Tehran on its nuclear program.