By Frank V. Pabian and Siegfried S. Hecker
Shortly after its failed April 13 rocket launch, North Korea was widely expected to conduct its third underground nuclear test. Such a test would have fit the pattern of the first two nuclear tests, both of which followed failed rocket launches and international condemnation. And Pyongyang has compelling technical, military, and political reasons to conduct a third nuclear test that would demonstrate it can miniaturize nuclear warheads to fit on a missile, making its nuclear arsenal more threatening.
We believe the first two North Korean tests used plutonium as the fissile material. Without at least one more successful plutonium test, it is unlikely that Pyongyang could have confidence in a miniaturized plutonium design. The country has a very small plutonium stockpile, sufficient for only four to eight bombs, but it may be willing to sacrifice some material to gain additional data to augment information already obtained from the previous two tests.