Iran is reportedly just weeks away from amassing enough weapons-grade uranium to build a nuclear bomb.

According to the International Atomic Energy Agency (IAEA), a nuclear device requires approximately 15 kg of 90% enriched uranium.  Iran’s stockpile of uranium gleaned from enrichment facilities at Natanz and Fordow stands at 60%.

While Iran maintains that its nuclear program is solely for peaceful purposes, there is no civilian use for such large quantities of highly enriched uranium.

Enriching uranium to levels suitable for nuclear weapons is a complex and time-consuming process. Natural uranium consists primarily of the non-fissile U-238 isotope, with the fissile U-235 isotope making up just 0.7% of the material. In order to power nuclear power plants, only a ratio of 3.5% U-235 is needed. Once uranium is enriched to 60%, it takes only about two more weeks of processing to reach the weapons-grade level of 90%.

During an event this weekend at the Aspen Security Forum, Secretary of State Antony Blinken delivered a similar warning.

“Iran, because the nuclear agreement was thrown out, instead of being at least a year away from having the breakout capacity of producing fissile material for a nuclear weapon, is now probably one or two weeks away from doing that,” Blinken said.

“They haven’t produced a weapon itself, but that’s something of course that we track very, very carefully.”

Last summer, an IAEA inspector discovered that Iran had briefly achieved an enrichment level of more than 80% due to modifications in its centrifuge piping. Although Iran’s enrichment levels temporarily slowed a bit, allegedly due to secret U.S.-Iranian talks, the country’s cooperation with the IAEA significantly deteriorated when the regime stopped issuing visas to the agency’s most top inspectors.