Setback for Iran’s Nuclear Program after Mystery Fire at Centrifuge Assembly Site

“The equipment inside the workshop was meant to be used for making precision measurements in assembling advanced centrifuges that are sensitive machines and difficult to build, because you have to ensure that they are identical,” Burkhard said. “We think the centrifuge equipment likely is not easily replaceable, because the components would be subject to international export controls,” she added.

Under a 2015 deal between Iran and world powers to curb Iranian activities that could be used to make nuclear weapons, a Joint Commission was set up to monitor Tehran’s procurement of certain nuclear and dual-use items to ensure that its nuclear work stayed within agreed limits.

The United States also sanctioned Iran’s Centrifuge Technology Company (TESA) in 2011 and since then has further sanctioned international companies in TESA’s procurement network.

U.S. President Donald Trump withdrew the United States from the Iran nuclear deal in 2018, saying it was not tough enough on Tehran, and began unilaterally imposing sanctions aimed at pressuring Iranian leaders to stop a range of perceived malign behaviors. Iran, which denies seeking nuclear weapons, has vowed to resist the U.S. sanctions, which have weakened its economy. Tehran also has been violating a series of limits on its nuclear activities since last year to try to pressure the 2015 deal’s remaining signatories to compensate it for the U.S. sanctions.

One of Iran’s violations has involved research and development of advanced centrifuges at facilities such as the fire-damaged workshop at Natanz. The Institute for Science and International Security is unaware of any other similar workshop in Iran, Burkhard said.

“The fire was a significant setback for Iran’s advanced centrifuge production,” she said.

Burkhard also said the damage to the facility was so large that it did not appear to have been caused by an industrial accident. Her colleague David Albright told The New York Times that he believed it was an act of sabotage, because the assembly of centrifuge components in the workshop would have involved few flammable liquids and was unlikely to be dangerous.

After downplaying the incident, Iranian state news agency IRNA issued a warning later Thursday, saying “if there are signs of hostile countries crossing Iran’s red lines in any way, especially the Zionist regime (Israel) and the United States, Iran’s strategy to confront the new situation must be fundamentally reconsidered.”

In an email to VOA Persian, Foundation for Defense of Democracies Iran analyst Behnam Ben Taleblu said the Iranian warning suggests that Tehran thinks its earlier assertions about the fire being an “accident” were not convincing enough for many Iranians who suspect foreign involvement.

The U.S. State Department said it was monitoring reports of the fire. In a statement sent to VOA, it said the incident “serves as another reminder of how the Iranian regime continues to prioritize its misguided nuclear program to the detriment of the Iranian people’s needs.”

“Iranian officials have a good reason to downplay foreign acts of sabotage on their soil, as it would expose them as incompetent,” Taleblu said. “How Iran responds to this, at home and abroad, will determine a great deal about the origins of the fire.”

Michael Lipin is editor and correspondent at VOA News. Farhad Pouladi works for VOA’s Persian Service. Barry Newhouse contributed.This article originated in VOA’s Persian Service.