The International Atomic Energy Agency (IAEA) confirmed on August 15 that Iran had introduced a second cascade of centrifuges capable of enriching uranium to 60 percent purity at the Natanz nuclear facility. The expansion doubles the Natanz facility's capacity to enrich uranium to 60 percent. Iran had previously shut down the second cascade in April, at the start of now-paused negotiations to return Iran and the United States to compliance with the JCPOA. Iran claimed to have stockpiled 8.9 kilograms of uranium enriched to 60 percent in July, up from 2.4 kilograms the previous month.