"An unfathomable mental power of all the people has erupted like an active volcano"

So that's what they were talking about:

On Monday, the country's official Korean Central News Agency said the regime "successfully conducted one more underground nuclear test on May 25 as part of measures to bolster its nuclear deterrent for self-defense."

The regime boasted that the test was conducted "on a new higher level in terms of its explosive power and technology of its control." [...]