60% enriched uranium

Nuclear stockpile

Iran's stockpile of near-weapons-grade uranium on the eve of the strikes, the core proliferation concern. The IAEA verified 408.6 kg on 17 May, which grew to 440.9 kg by 13 June, the day before the attacks. Since the strikes the Agency has lost continuity of knowledge and cannot verify its size or whereabouts; satellite imagery suggests most was moved into the Isfahan tunnel complex around 9 June.