Ping!
This is going to end, badly. Very badly.
I would think Nobel Gases would decay via alpha particles and would be difficult to detect from a distance, which is why we would need to fly directly over NK.
The stand-in for Savage on the radio this evening concluded that the nuclear test combined with rocket launches is really advertising. They are telling the world they are open for business to supply nuclear warheads and delivery systems.
Since the NorKs announced the test in advance, albeit shortly in advance, it seems more like bristle and bluster than clandestine subterfuge.
The North Koreans would appear inexorably to be - as we used to say in the Fifties - cruisin’ for a bruisin’.