It's suspicious for sure. I'm well aware of the capabilities you have described for detection methods and is more likely what would be the purpose such as LIDAR. Looking for what, I or anyone doesn't know yet. Btw dirty does not mean leaky it means uncharacterized. As far as nuke sniffing and air sampling that is very specific conditions it would be used in. Key words their is air sampling, that is a physical collection and assay and not remote detection analysis which is the speculation where a drone is just sitting in the air "scanning" for nukes. Lol.

If that's what is occurring then that is a major problem as it would indicate radioactive particulates in the air, above ground and massive area would be in serious jeopardy right now, and folks better start making arrangements, dependant on the intensity and type of this fictional material being speculated.

Again nuke sniffing, with some floating craft to find radio-isotopes is not a thing, and if it is, mankind's understanding of physics will need to be reevaluated and changed.