Iran Has Accelerated Construction Of A Classified Nuclear Facility Underground
- 27.09.2025, 10:28
Tehran's actions are being watched closely in the US.
Iran has accelerated construction of a classified nuclear facility under Kirk Mountain. It is located near the Natanz nuclear complex, which was hit by devastating U.S. strikes in late June this year.
The Iranian authorities have prevented an IAEA mission from entering the site despite requests from the agency, raising suspicions of Tehran's attempts to restart its nuclear program. Details are reported by The Washington Post.
Iran has accelerated construction of a new underground facility
After US and Israeli strikes on Iran's main nuclear facilities in June this year, Tehran is accelerating construction of a new classified underground facility. Experts speculate, this may indicate that Iran has not given up its intentions to obtain nuclear weapons - and is trying to cautiously rebuild its nuclear program.
Work continues at the Kuh-e-Kolang Gaz La (Kirka Mountain) site. There, deep in the Zagros mountain range, less than two kilometers south of the U.S.-broken Natanz nuclear complex, Iranian engineers have been tunneling since 2020.
What exactly is going on underground and what the purpose of the facility under construction actually is is not known. Iran does not allow IAEA inspectors to visit the site, and Tehran rejected the agency's last request in early September.
Experts estimate that the underground rooms under Kirk Mountain may be deeper than in the American-bombed Fordow - up to 100 meters deep. That means the facility may be more secure.
At the start of construction five years ago, Iran said it was setting up a manufacturing plant there to assemble centrifuges - fast-moving machines for enriching uranium - to replace a similar facility destroyed earlier in 2020 as a result of "sabotage."
An analyst for the satellite company Maxar says construction of the tunnels began in December of that year. Their size and depth have raised suspicions among analysts that they are for other purposes: Tehran may be planning to house either a secret uranium enrichment facility there, or use the site as a safe place to store Iran's near-weapons-grade uranium stockpile.
At the same time, experts note: building under the mountain and on its top does not mean that Tehran is in a hurry to resume its nuclear program and is fast approaching the creation of a nuclear bomb.
The United States is watching Tehran's actions closely, the administration of President Donald Trump assures.
"The administration will continue to monitor any attempt by Iran to resume its nuclear program. As President Trump has said, he will never allow Iran to obtain a nuclear weapon," one official said on condition of anonymity.
The site under Kirk Mountain has been monitored by U.S. intelligence agencies since its inception. However, the CIA declined to comment on the matter to The Washington Post reporters.
In the meantime, the IAEA claims that Iran had stockpiled more than 400 kilograms of uranium enriched to 60% purity before the Israeli-American strikes (uranium enriched to 90% purity is needed to build a nuclear bomb). No one knows what happened to this stockpile, which only fuels fears that Tehran will eventually use it to build nuclear weapons.
When building the facility, Iran took into account the experience of bombing of its other nuclear facilities by Israel and the US, so it is taking measures to protect the new building from future attacks or possible infiltration - and is probably expanding the facility, especially its underground part.
Three experts on Iran's nuclear activities have analyzed satellite images of the site taken after the U.S. strikes - and found several major markers of increased construction. These include:
reinforcement of the security perimeter (since late June, 1,200 meters of security wall - that's almost the entire perimeter - has been erected and a new road has been built along it);
strengthening of structures at the tunnel entrance;
increased excavated rock.
And recently, heavy and construction equipment has been found in the construction area.
"The presence of dump trucks, trailers and other heavy equipment ... indicates continued construction and expansion of the underground facility," convinced Joseph Rogers, a research associate at the Center for Strategic and International Studies.
According to Sara Burkhard of the Institute for Science and International Security, the concrete frame of one of the tunnel's eastern entrances covered with earth and rocks indicates the construction of at least one other route to the underground facility.
"The reason for covering the tunnel entrance ... is to reinforce it against airstrikes, [making it more difficult for] the entrance to collapse," she opined.
What Tehran is saying
Iranian President Masoud Pezeshkian said the other day that his country will remain a party to the nuclear nonproliferation treaty - despite the fact that not everyone in power inside Iran supports such a decision.
"We have no intention of leaving the NPT," Pezeshkian told reporters.
The statement came on Friday, September 26 - and marked a definite change in tone for official Tehran, which has been making contradictory statements since the US strikes, writes Bloomberg.
"After European states decided to renew nuclear sanctions against Iran that were lifted as part of a 2015 nuclear deal with the US and other countries, diplomats feared Tehran would pull out of the landmark international deal aimed at preventing the spread of nuclear weapons. Pezeshkian's assurance came on the same day - and at the same time - that the U.N. Security Council voted to reinstate broad sanctions against Tehran.... The sanctions, lifted as part of the 2015 agreement, will go into effect Saturday night New York time," the publication notes.