The International Atomic Energy Agency (IAEA) reported on March 31 that Iran began using a fourth cascade of 174 second-generation IR-2m centrifuges to enrich uranium at the Fuel Enrichment Plant (FEP), the underground portion of the Natanz nuclear facility. Iran has also installed an additional two cascades of IR-2m centrifuges but has yet to begin operating them; Iran has informed the IAEA that it plans to eventually use the total of six cascades to enrich uranium to 5 percent purity. The IAEA also noted that Iran had yet to start installing an intended second cascade of IR-4 centrifuges. The Joint Comprehensive Plan of Action (JCPOA), the international agreement limiting Iran's nuclear program that Iran has been in breach of since 2019, restricts the country to the use of less efficient IR-1 centrifuges at the FEP. According to the IAEA, Iran is now using 30 cascades of 5,060 IR-1 centrifuges, four cascades of 696 IR-2m centrifuges, and one cascade of 174 IR-4 centrifuges to enrich uranium at the FEP.