The centrifuges “in operation” in Natanz are located in two places. The first site is the two main production halls A and B, which have a capacity of about 20,000 centrifuges and were buried underground in 2004 after the nuclear program was leaked to reduce their vulnerability to possible air strikes.The second site is the Natanz Enrichment Pilot Center (PFEP), where smaller waterfalls (less than a few thousand centrifuges) are installed for experimental purposes by researching new centrifuges or arrangements for higher percentage enrichment. According to Borjam, all research centrifuges must be installed and tested “on the ground” in this center …With the destruction of the assembly center in the recent attack, the J.A. Advanced centrifuges have been drastically reduced, and what Bloomberg reports is that the transfer of the remaining number of advanced centrifuges from the pilot’s ruminant center to the main underground production halls [to protect against future attacks] is not a new installation.Footnote: This transfer to underground facilities is another evidence of the origin of the recent Natanz incident. The transfer of the remaining centrifuges to the underground shelter set up to withstand air strikes in about a month signals protection priorities that it does not conform to the hypotheses of a security source for the Natanz incident.