- The 10X tremor strength reported by Japan is easily in range of a large boosted fission weapon, such as the British Orange Herald device.
- The North Koreans mastered radiation implosion on their first try. Since this is unlikely, it would indicate a major intelligence failure.
- A third path of proliferation, providing a turn-key design.
Although open-source does not give us access to the U.S. intelligence product, there is usually a parallel in open source analysis that approximates it. But it’s not out there.
Since the North Korea pattern is to announce events that are somewhat in advance of actual progress, it is possible that the strata, the rock in which the test device was placed, was deliberately chosen to be harder than usual. This would increase the signal received by distant seismic detectors.
So this estimate is that the North Korea test was of a boosted fission weapon, similar to Orange Herald.