Iran then stated last year that Fordow would instead house some of Iran's most sensitive uranium enrichment to 20 percent purity – high enough for the bespoke reactor fuel it needs for a small research reactor it has in Tehran, but not the 90 percent required for a weapon. Iran's claims in the media that it had completed setup and used its most sophisticated centrifuge cascades at Fordow proved untrue, according to the IAEA.
In its latest design change a month ago, Iran inexplicably added back the 5 percent enrichment, alongside the 20 percent, and scrapped an R&D element.
Iran doubled the number of installed centrifuges in the past three months to almost 700. But they are all the most basic IR-1 variety, Iran's first-generation machine with a decades-old design. The IAEA reported that a further 2,088 empty centrifuge casings had been placed at the site – but all of them are also for the IR-1.
UN Security Council: questions must be resolved
Several UN Security Council resolutions – four of them imposing sanctions – require that Iran halt all enrichment activities until the questions about any weapons-related work are resolved.
Iran says it only wants to make nuclear power peacefully, and this week, Supreme Leader Ayatollah Ali Khamenei said having nuclear weapons was a "sin."
"The Iranian nation has never been after nuclear weapons and it will never go after such weapons," Ayatollah Khamenei told nuclear scientists, at least four of whom have died in the last two years in targeted assassinations that Iran blames on Israel. "The Iranian nation will prove to the world that nuclear weapons do not bring about power."