There have been increasing signs in recent days that the North Korean government is considering a fourth nuclear test – at least, this is what recent Foreign Ministry statements have suggested. On March 30, it reportedly said: "We will not rule out a new form of a nuclear test aimed at strengthening our nuclear deterrence."

In the past, there have been some false alarms, but earlier nuclear tests were often preceded by some kind of official signal from North Korean media that a test was imminent. The chances are relatively high therefore, that in the next few weeks another underground explosion will shake mountains in a distant part of North Korea near the Chinese border.