Originally Posted by
tartare
HEU possibly under the scenarios you outline, but tracking of hundreds of targets by IMINT or ELINT is indeed feasible.
These systems deployed at altitude can visually monitor an entire city, and effectively re-wind what they see.
Google the term Wide Area Persistent Surveillance.
Effectively they are military digital video surveillance recorders paired with highly sophisticated multi-lens camera systems, and software which can stitch the imagery together enabling analysts to zoom in on parts of the image - highlight an object or person of interest and then backtrack a path.
Let's assume (for the sake of argument) that US intel can track every vehicle movement in Iran with 100% accuracy. Now consider that the Iranians move all of their 400kg of HEU in 1 vehicle movement and the US know
exactly which day this will occur. They observe 50 vehicle movements at the Fordow facility on that day and each of these vehicles moves to a logistics hub/ warehouse. There are a further 50 vehicle movements from each of these hubs each going to a final location. That is now 2500 possible locations for your HEU on day 1! Now consider that 50% of these secondary movements are also to hubs, and that vehicle movements follow the same pattern the next day. By the end of day 2, you have ~63k possible locations and by day 3 you are close to 1M. If you target trucks as they leave the facility, that might be doable with an airstrike. Otherwise, you will need additional sources of intelligence.
In reality, the HEU will be widely dispersed with multiple dummy containers and a very few people who know which is which. Logistically it is much easier to store HEU out of the reach of US and Israeli weapons than it is to do the same with a processing facility. I have no doubt that Israeli intelligence capabilities in Iran are exceptionally good but I very much doubt that they (or the US) have the capability to target Iranian HEU inventory with airpower alone.
Edit: This should not be a surprise to anybody who has posted a letter. Imagine claiming that because you saw me post a letter, and you could log movements of every postal truck, that you would be able to tell who I had sent it to without seeing the envelope!