This summer, Iran decided to construct a new underground centrifuge assembly plant, following the destruction of the above ground one at the Natanz enrichment site on July 2, 2020. So far, Iran has undertaken little visible work in the mountains adjacent to the Natanz enrichment site with the exception of possible construction preparations. A nearby gunnery range appears to have been converted to a construction support and staging area in the first half of September. Because of the added difficulties of building an underground site, the completion of a new centrifuge assembly plant able to assemble thousands of advanced centrifuges per year is unlikely in 2021.

In early September 2020, Iran announced its earlier decision to replace its Iran Centrifuge Assembly Center (ICAC), destroyed in early July of this year, with a new facility in a mountain near the Natanz uranium enrichment site. According to Ali Akbar Salehi, head of the Atomic Energy Organization of Iran (AEOI); “It was decided to establish a more modern, wider and more comprehensive hall in all dimensions in the heart of the mountain near Natanz. Of course, the work has begun.” The destroyed site was designed to assemble thousands of advanced centrifuges each year. Its destruction set back Iran’s plans to expand its centrifuge program by at least a year and perhaps longer. Exactly how long will depend on Iran’s ability to rebuild the new facility, outfit it with sensitive equipment, and bring it into operation.

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Read the full report at the Institute for Science and International Security.