The North Koreans detonated a nuclear device in February, apparently their third. Based on seismographic measurements, its estimated yield was 10 to 20 kilotons, about that of the bombs dropped on Japan in 1945. It’s unlikely that the North Koreans simply mass-detonated a great deal of conventional explosive. The seismic signals from such an event apparently would differ from those produced by a nuclear explosion because it would be nearly impossible to trigger all of the explosives simultaneously enough. The U.S. Air Force sent in a specialized nuclear “sniffer” aircraft to collect air samples after the explosion. They may provide evidence of the character of the device. Reportedly this explosion was double the magnitude of the last one, which in turn was much more powerful than the first. Pakistani and Indian nuclear tests also have produced only limited yields, enough to cause serious damage, but nothing on the scale produced by the declared nuclear powers.
It is doubtful that the North Korean device is small enough to be lifted by the long-range missile the country recently tested. With only three tests under their belts, the North Koreans are probably still learning how to produce viable weapons rather than devices. They may see nuclear tests more as a way of gaining respect and attention. Unless North Korea presents a viable threat to the outside world, why deal with it? The North Koreans have learned that it pays to flaunt violations of the rules the United States and others try to impose. Moreover, new leader Kim Jong-un must demonstrate assertiveness to his colleagues, many of whom undoubtedly would like to replace him.
Weapons and their technology are North Korea’s main exports. One report had Iranians present at the most recent North Korean test. Pyongyang’s latest offering may be plutonium extraction from used reactor fuel rods. According to recent reports, Iran has activated a heavy-water plant (steam from the plant is visible in commercial satellite photographs). Satellite photographs also show heavy air defenses arrayed around the plant, albeit using obsolete weapons such as the Iranian upgrade of the U.S. Hawk system. The only plausible purpose of such a plant would be to provide the moderator of a home-grown reactor, which could produce plutonium.