Suppose some little country wants to start working with U and Pu. So, they set up a building, get it some utilities, surround it with some security, and then g

Suppose some little country wants to start working with U and Pu. So, they set up a building, get it some utilities, surround it with some security, and then go shopping for a long list of lab supplies and equipment. Then, likely, presto, bingo, the intel agencies of the more advanced countries will notice what is going on inside the building just from what is on the purchase orders going outside the building. Then have some drones and/or satellites fly over the building with some neutron or gamma ray detectors or some such. Then have a little chat with the leaders of that little country. I'm not sure it would be easy to hide such activities now. And if they do get some fissionable materials, then they would have to test a bomb, and can't hide that.