At the time, it was divided into four geographical sectors by the Iranians. Using satellite and other data, inspectors were allowed by the Iranians to choose any sector, and then to visit any building inside that sector. Those 2005 inspections included more than five buildings each, and soil and environmental sampling. They yielded nothing suspicious, but did not include the building now of interest to the IAEA.
"The selection [of target buildings] did not take place in advance, it took place just when we arrived, so all of Parchin was available," recalls Heinonen, who led those past inspections. "When we drove there and arrived, we told them which building."
Since then, the IAEA says it has new information about a large explosives containment chamber installed in 2000. Experiments designed to simulate the first stages of a nuclear explosion, as suspected at Parchin, the IAEA stated last November, are “strong indicators of possible weapons development.”
IAEA experts requested visiting Parchin during two visits to Tehran in January and February, but were refused. IAEA Director General Yukiya Amano issued a terse statement, saying it was "disappointing that Iran did not accept our request."
Days later, the IAEA’s quarterly report on Iran explained that Parchin was part of a larger negotiation. It stated that "modalities" had not been agreed with Iran to satisfy "Iran's security concerns, ensuring confidentiality, and ensuring that Iran's cooperation included provision of access for the Agency to all relevant information, documentation, sites, material and personnel in Iran."
Five Iranian scientists linked to its nuclear programs have been assassinated in Iran in the past two years, actions that Tehran blames partly on "leakage" of confidential information from the IAEA.