Uh, I guess what I am trying to say, is that a satellite would have to be over an undergound test site to detect a nuclear test. Oh, and I don't think we are flying AWAC's or EP-3s over the North Korea territory, hehehe.......
I would love to sit here a give you an idiot lesson about how sensitive our atmospheric monortoring satellites are and their ability to detect even the slightest change in temperature along with pinpointing the source, But I will let you do your own research. For that mnatter, just turn on the weather channel,