What took place at the Iranian Natanz nuclear facility?

The incident is the third mysterious explosion in a week and has led to many questions.

A general view of the Bushehr main nuclear reactor, Iran (photo credit: REUTERS/RAHEB HOMAVANDI)
A general view of the Bushehr main nuclear reactor, Iran
(photo credit: REUTERS/RAHEB HOMAVANDI)
The plot thickened last Thursday afternoon hours after a building at a nuclear facility in Iran appeared to have blown up. Reports of an “explosive device planted” and an early warning, as well as a dissident group taking responsibility, add to questions and concerns about what happened at the sensitive site.
The building affected by some kind of an explosion is located at the Natanz nuclear enrichment facility. Iran had alerted the world to the incident in the morning of July 2 and even took state media for a tour to show that while there had been some kind of incident, the nuclear facility was not in danger. It was the third mysterious explosion in a week and has led to many questions.
“A Middle Eastern intelligence official... said the blast was caused by an explosive device planted inside the facility,” The New York Times reported. “The explosion, he said, destroyed much of the aboveground parts of the facility.”
This is important because it was allegedly the aboveground portion of a larger area where new centrifuges are “balanced before they are put into operations.” Iran is known for building underground facilities that obscure or protect their activities, including at missile and nuclear sites.
 
It now looks increasingly likely the incident was a deliberate attack or act of sabotage. Adding to the question of how this happened, a group called the “Homeland Panthers” claimed responsibility, according to emails allegedly sent to BBC Persian.
The emails arrived “hours before any news of the incident had emerged,” according to Radio Farda. The emails, however, claimed something more complex. They asserted there was an attack and then a cover-up. They wanted to blow the lid on the cover-up.
The attack apparently happened at around 2 in the morning on July 2. It was not widely reported in Iranian media until some eight hours later. IRIB News gave a tour in the afternoon of the area that was burned.
The US National Oceanographic and Atmospheric Administration has data from a satellite that tracks fires showing one at around 2 a.m., the Associated Press reported. This corresponds with someone on the ground who allegedly heard an explosion.
The AP report quotes Fabian Hinz of the James Martin Center for Nonproliferation Studies as noting the fire took place at a new centrifuge production facility. David Albright of the Institute for Science and International Security agreed that the fire was at a new production facility. This would be a setback for Iran’s production and could delay the advancement of centrifuge technology, Hinz said.
Iran may be hinting at threats to Israel now. An analysis piece at IRNA news said the “Zionist regime and the US” were crossing red lines.
 
Natanz has been struck in the past. In 2010, workers found that high-speed centrifuges had been sabotaged by the Stuxnet computer worm. In November 2019, as Iran began to walk away from the Iran nuclear deal in response to the US exiting the deal, the Atomic Energy Organization of Iran said it had doubled the number of advanced centrifuges at the site. Iran had previously agreed to install only 5,060 of the less-efficient centrifuges it had at Natanz until 2026. An inspector of the site was also denied entry the same month.
This means it was widely known last year that Iran was progressing with enrichment at Natanz. According to reports at the end of last year, it had unveiled 30 IR-6 centrifuges, and there were 60 of these spinning at Natanz at the time.