The discovery of enriched uranium at the undeclared sites is one of the key issues blocking the Vienna negotiations on reviving the 2015 nuclear deal. The agreement is intended to prevent Iran from building the atomic bomb. The head of Iran's nuclear agency, Mohammed Eslami, announced on the eve of the IAEA visit that Iran had increased its uranium enrichment capacity. The state news agency IRNA quoted him as saying that these capacities are now twice as high as ever.