The IAEA confirmed that “Iran had begun feeding natural UF6 into a fourth cascade of 174 IR-2m centrifuges” in Natanz, noting: “as of 31 March 2021, the Agency verified that Iran was using 5,060 IR-1 centrifuges installed in 30 cascades, 696 IR-2m centrifuges installed in four cascades and 174 IR-4 centrifuges installed in one cascade to enrich natural UF6 up to 5 per cent U-235 at FEP”.