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October 10, 2025: Three years ago, Iran's response to Israeli attacks on its two underground nuclear fuel production sites at Natanz and Fordow was to build the new Kuh-e Kolang Gaz La underground facility near the Natanz site. The new operation is 1,600 meters underground, 50 percent deeper than Natanz or Fordow. The space available inside Kuh-e Kolang Gaz La is about 50 percent less than the two current underground sites. Iran is installing more efficient centrifuges there to match current Natanz/Fordow production while occupying less space. The new facility may be more difficult to disable with an airstrike, but the last two attacks were carried out using malware or bombs planted by Israeli Mossad operatives, with the assistance of Iranians opposed to the current Iranian religious dictatorship and its obsession with creating nuclear weapons.
Iran continues to work on nuclear weapons. In 2021, the International Atomic Energy Agency (IAEA) reported activity at Iran's Natanz underground nuclear fuel enrichment facility. Israel had smuggled a large bomb into Natanz and detonated it on April 11. The IAEA reported on Natanz's enriched uranium production 54 days before the April explosion and 40 days after it. Iran initially called the explosion an accident. Within a week, Iran admitted the explosion was an attack that caused major damage to their new high-performance nuclear enrichment system, which turned uranium into weapons-grade material. IAEA inspectors were allowed to view the damage, and the recent IAEA report provides details of Natanz operations before and after the April explosion. The IAEA found that between February and May 2021, Iran enriched 335.7 kg of uranium ore to five percent Uranium-235. Unenriched uranium ore is only about 0.7 percent U-235. Uranium enrichment is a process that increases the content of Uranium-235 in uranium ore sufficiently for nuclear applications.
Soon after the April explosion, Iran was hard at work repairing the damage at Natanz, their most modern and productive enrichment facility. The other enrichment facility is at Fordow, also underground. Together, these two facilities operate 5,060 centrifuges, and Iran has another 13,000 centrifuges in storage to replace those that wear out or are lost to accidents, deliberate sabotage, or attacks.
The April 2021 bomb attack on Natanz caused massive equipment failure and damage on a scale similar to the 2010 attack carried out with malware against the heavily guarded Natanz compound and its computer-controlled uranium centrifuges. Later analysis indicated that the 50-meter-deep underground factory was effectively destroyed by the 2021 explosion. The target was its thousands of centrifuges. Israeli hackers accessed the centrifuges in 2010 via a computer worm called Stuxnet. A worm is malware that infiltrates target systems via stealth and physical media like USB thumb drives. Stuxnet was released four or five years before it reached Natanz, apparently via a USB drive containing the normally invisible malware. Once that USB drive is used on any local or internet-connected computer, Stuxnet automatically copies itself onto all computers connected to the network, especially industrial microprocessors used to control equipment. Stuxnet checked for centrifuge systems and disrupted their operations.
The 2021 attack required several years of preparation. The Israelis first obtained technical details of the Natanz electrical system and the new generation of centrifuges Iran installed there. The Israeli plan used explosives detonated where they would shut down the primary and backup power systems when the maximum number of new centrifuges were powered up and vulnerable to severe damage if these systems failed simultaneously. This worked as intended, and Natanz again suffered major centrifuge loss that took months to restore to production and over a year to completely fix.
Needed security upgrades were uncertain until Iran could learn more about exactly how the attack was carried out. They knew a lot of explosives were involved but were unsure how the attackers determined how and where to place them without being discovered. To aid in solving that mystery, Iran went public with details and the name of a suspected key operative. Iran is looking for Reza Karimi, a 43-year-old Iranian who left the country several days before the attack. Other Iranians were involved, as well as suspected Israeli Mossad agents who came to Iran and worked with a growing number of Iranians seeking to overthrow the current religious dictatorship. The Iranians have been seeking more of these Mossad-linked Iranians since a 2018 Mossad operation in the capital, when a heavily protected warehouse containing top-secret documents was covertly entered, half a ton of documents on the Iranian nuclear program were removed, and 24 hours later, they showed up in Israel. Until 2021, Iran denied this Mossad operation occurred.
There were no casualties at Natanz because of the bomb, which was a deliberate part of the attack plan. As a result, many Iranians supported the attack, and Iranians living outside their homeland openly expressed their hostility toward the Iranian nuclear program.
The two attacks on Natanz were very damaging to Iran's claims that it does not have a nuclear weapons program. In the aftermath of both attacks, it became clear that Iran was using powerful new centrifuge designs to create nuclear material far more refined (above 20 percent) than needed for a nuclear power plant. Iran needed hundreds of kilograms of U-235 refined to 90 percent to make enough nuclear weapons to deter further attacks and/or destroy Israel. The data Mossad made public in 2018 and the aftermath of the 2021 attack demonstrate that Iran was still seeking nuclear weapons.
The growing number of Mossad operations in Iran has led to public criticism, often by the senior clerics who rule the country. There has been more public criticism in Iran because the government has, for decades, devoted major resources to destroying Israel. That effort has consistently, and often spectacularly, failed at great cost to Iran. This makes the religious dictatorship look incompetent, as these senior clerics always insisted they were doing God’s work. The 2021 Mossad attack made many more Iranians realize that Mossad was apparently entrenched inside Iran and finding more Iranians willing to work with Mossad against projects that many Iranians agreed were endangering and impoverishing Iran, contributing to declining living standards and growing crackdowns by the Islamic Revolutionary Guard Corps (IRGC) and police. The IRGC knew that the Israelis had been successful at establishing a clandestine Mossad presence in Arab nations but thought Iranians were too loyal for this to happen in Iran.
Iran is trying to portray itself to foreigners as the innocent victim of Israeli aggression. Iranians insist that Natanz was only producing enriched uranium suitable for power plant fuel. However, recent IAEA reports describe evidence that Iran is seeking to develop a nuclear bomb and needs highly enriched (to 90 percent purity) U-235 for that. Foreigners are not as easily deceived as before, and more questions are being asked about Natanz. Inside Iran, the “accidental” fire at Natanz in mid-2020, described as a construction accident, is now being revisited as details emerge of how Mossad agents inside Natanz got 150 kg of explosives into the underground complex and managed to hide them, along with their remote-control detonators, where they would not be found and would do maximum damage when detonated.
Even before the bold Israeli attack on Natanz, Iran was violating the IAEA inspection requirements for the 2015 treaty that lifted Iranian economic sanctions. Since Natanz was bombed in 2021, Iran has announced further restrictions on the IAEA and is demanding that full compliance with the 2015 treaty be restored before Iran will negotiate the restoration of IAEA inspections. This is unacceptable to the United States, where a new government came to power in early 2021 and announced it was not willing to rejoin the 2015 treaty that the previous government had suspended in 2017 because Iran was cheating on the nuclear weapons restrictions of the 2015 treaty. Those accusations proved to be true, and Iran is not changing its negotiating tactics.
The threatened Israeli airstrikes never had the underground enrichment facilities as a primary target. An Israeli airstrike would target surface facilities vital to the nuclear weapons or ballistic missile program. What bothers Iran is that Israel likely knows much more about those other targets and the extent to which their destruction would cripple the Iranian nuclear and ballistic missile programs. This is a more worrisome Israeli threat, especially their ability to do what Iranian leaders believed unlikely or impossible.
This was most recently demonstrated on June 25, 2025, when 200 Israeli warplanes carried out a surprise attack that eliminated most Iranian air defenses. Many facilities needed to develop and build nuclear weapons were destroyed, along with over a dozen key nuclear scientists and military leaders.
By mid-2025, Iran had not recovered from this and concentrated on rebuilding its air defense system with Chinese systems. This is being done while the Israelis observe, take notes, and plan another attack.
Even if Iran acquired nuclear weapons, Israel is ahead of them, with ballistic missiles and submarines capable of launching nuclear-armed missiles.