Iran Accelerates Underground Fortifications at Natanz Nuclear Site
Satellite imagery shows Iran expanding underground fortifications at the Kuh-e Kolang Gaz La nuclear site near Natanz following US threats, alongside repair work at Parchin.
New satellite imagery reveals that Iran is continuing to expand fortification works at the Kuh-e Kolang Gaz La mountain, a deeply buried underground complex located near the Natanz nuclear facility. The site has recently been designated by US President Donald Trump as a potential target for a strike. According to a report published by the Institute for Science and International Security, satellite photos from September 11 show earth berms blocking tunnel access roads, alongside a significant thickening of soil layers over the entrances to harden them against aerial penetrators.
Hardening Underground Facilities
Experts at the institute assess that the massive soil additions are intended to increase the buffer material over the entrances, thereby substantially complicating any potential airstrike. Restricting access to the location reinforces the assessment that the site is not currently in routine use, though sensitive and high-value materials or equipment may be stored inside. The acceleration of these fortifications comes days after an explicit warning from President Trump, who told reporters that the US is closely monitoring activity at the site.
We are noticing that there is some activity at Pickaxe. I would advise Iran not to try to get smart, because we would have to hit them very hard.
Trump had already declared in late July that the United States monitors the site and could eliminate it if the diplomatic track fails. The complex at Kuh-e Kolang Gaz La was established about two kilometers from Natanz following a 2020 sabotage operation at the centrifuge assembly plant, serving as a protected underground response. Experts estimate that parts of it are buried at a depth of at least 100 meters underground, surpassing even the depth of the Fordow facility and presenting a complex operational challenge for destruction.
Activity at Parchin Complex
Meanwhile, the institute's report also revealed fortification and camouflage activity at the Taleghan 2 facility within the Parchin military complex. Satellite photos from September 13 show a giant tarp installed to conceal the structure from satellite surveillance, while bulldozers, concrete mixers, and cranes operate around it to erect new concrete reinforcements. The Parchin facility sustained damage during Israeli strikes in October 2024 and March 2026, and Tehran appears to be working intensively to rehabilitate and fortify it against further air raids.
