Inside job is my guess. It wouldn’t take a lot. It takes hydrofluoric acid to make uranium hexafluoride, and that stuff is highly corrosive and forms explosive gases when it gets out and touches the wrong material. Rupture a tank and head for the hills.
Does the U.S. still use centrifuges for isotope separation? The patent was declassified in 1954, I thought, because it was believed that “no one would ever do it that way again”?
I find it fascinating that the U.S. was able to fight a World War, and built an atomic bomb at the same time, in under four years, and Iran hasn’t been able to do it yet.