>>The 2006 DPRK test was confirmed by air sampling. The 2009 test did not vent enough. Don’t know about this one. Inspectors went to the DPRK in the 1990s and were given samples of weapons grade Plutonium. There is no doubt the Norks can make Pu-239. The amount of conventional explosives needed to equal a kiloton is very large. I would expect it to be noticed.
I remember the 2006. The radionuclides were only found weeks after when people noticed that there were none. There were none in 2009. Why not just process the 300000 tons of free urea based fertilizer into urea nitrate and blow it up? I don’t doubt it’s a nuke, but that sounds more feasible.
The Norks want a nuclear weapon. They have everything needed to make one so why try to get away with using ANFO?
The DPRK has been working on a nuclear weapon since at least the 1980s.