In February 2010, the IAEA issued a report scolding Iran for failing to explain purchases of sensitive technology as well as secret tests of high-precision detonators and modified designs of missile cones to accommodate larger payloads. Such experiments are closely associated with atomic warheads.
In May 2010, the IAEA issued a report that Iran had declared production of over 2.5 metric tons of low-enriched uranium, which would be enough if further enriched to make two nuclear weapons, and that Iran has refused to answer inspectors’ questions on a variety of activities, including what the agency called the “possible military dimensions” of Iran's nuclear program.
In July 2010, Iran barred two IAEA inspectors from entering the country. The IAEA rejected Iran's reasons for the ban and said it fully supported the inspectors, which Tehran has accused of reporting wrongly that some nuclear equipment was missing.
In August 2010, the IAEA said Iran has started using a second set of 164 centrifuges linked in a cascade, or string of machines, to enrich uranium to up to 20% at its Natanz pilot fuel enrichment plan.
In November of 2011, IAEA officials identified a "large explosive containment vessel" inside Parchin. The IAEA later assessed that Iran has been conducting experiments to develop nuclear weapons capability.