The new Natanz underground complex, located in the mountainous area south of the main uranium enrichment site, will feature halls more deeply buried than the Fordow uranium enrichment site, itself deeply buried. Both are significantly deeper underground than the buried centrifuge halls at the main Natanz site, each only eight meters below ground.
Given the size of the mountain, the new underground complex also has the potential to be much larger in floor space than the Iran Centrifuge Assembly Center (ICAC), an aboveground facility at the main Natanz site destroyed in July 2020 and slated for replacement in the new underground facility. The potential size of the underground complex raises questions about what capabilities this new tunnel complex will provide in addition to a new advanced centrifuge assembly plant. A Western intelligence official recently stated that there is strong reason to believe that an enrichment plant is being built at the Natanz underground site, and reiterated the claim in a follow-up conversation. The Institute was not able to independently confirm this, but a small, advanced centrifuge enrichment plant is certainly the most worrisome possibility.
Read the full report at the Institute for Science and International Security.