The outside of the centrifuges are moving at the speed of sound, 80,000 RPM+. That creates a harmonics we can hear. All enrichment gives off radiation of many different kinds, some particles travel through the Earth. Hard to detect, but doable and we are. The Iranians are up front about enrichment levels because they know that we know.
They also learned from Saddam that WMD's are not something to brag about and get yourself attacked.
Loose lips etc. Oh, see that they know that we know.
Bluffing about nukes without having a hole card is likely to be destabilizing. I’m glad to hear that they haven’t fine tuned. Also, clean room tech isn’t so easy. I know just enough to be dangerous, so I’ll quit.