detonators and modified designs of missile cones to accommodate larger payloads, experiments closely associated with atomic warheads. May 2010 report In May 2010, the IAEA reported that Iran had declared production of over 2.5 metric tons of LEU, 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 had 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 to enrich uranium to up to 20% at its Natanz Pilot Fuel Enrichment Plant. November 2011 report In November 2011, the IAEA reported that inspectors had found credible evidence that Iran had been conducting experiments aimed at designing a nuclear bomb until 2003, and that research may have continued on a smaller scale after that time. IAEA Director Yukiya Amano said evidence gathered by the agency "indicates that Iran has carried out activities relevant to the development of a nuclear explosive device." A number of Western nuclear experts stated there was very little new in the report, and that media reports had exaggerated its significance. Iran charged that the report was unprofessional and unbalanced, and had been prepared with undue political influence primarily by the United States. In November 2011, IAEA officials identified a "large explosive containment vessel" inside Parchin. The IAEA later assessed that Iran had been conducting experiments to develop nuclear weapons capability. The IAEA Board of Governors passed a resolution by a vote of 32–2 that expressed "deep and increasing concern" over the possible military dimensions to Iran's nuclear program and calling it "essential" that Iran provide additional information and access to the IAEA. The United States welcomed the resolution and said it would step up sanctions to press Iran to change course. In response to the IAEA resolution, Iran threatened to reduce its cooperation with the IAEA, though Iranian Foreign Minister Ali Akbar Salehi played down talk of withdrawal from the NPT or the IAEA. February 2012 report On 24 February 2012, IAEA Director General Amano reported to the