The chubby dictator could be forced to abandon his Punggye-ri nuclear test site after a series of earthquakes struck the region in recent months.
The destabilising tremors came after North Korea detonated a nuclear weapon – claimed to be a hydrogen bomb – at least five times more powerful than the blast at Hiroshima in World War 2.
The test sparked a massive 6.1 magnitude earthquake underneath the secretive base, which has since been hit by subsequent quakes, measuring 2.6 and 3.2 as a result of “geological stress” caused by the first explosion.
Now analysts from monitoring website 38 North believe the Mt Mantap site may no longer be suitable for further tests amid fears the base could collapse – putting thousands at risk.
The analysts played down reports that the rogue regime may have “nuked itself out of a nuclear test site”.
But they indicated the H-bomb test on September 3 caused “substantial damage” to the network of tunnels underneath the mountain base.
And if the site were to collapse, a plume of radioactive material could waft across the Korean peninsula – killing millions.
Analysis from 38 North said: “Based on the severity of the initial blast, the post-test tremors, and the extent of observable surface disturbances, we have to assume that there must have been substantial damage to the existing tunnel network under Mt Mantap.
“If North Korea were to attempt to continue testing under this mountain, then we would expect to see new tunnelling in the future near the North Portal, still under Mt Mantap.
“A lack of new tunnelling in this area would provide evidence that this mountain has been abandoned for future testing.”
September’s nuclear test was so strong that it shook buildings in Russia and China and was described as a “perfect success” by North Korea’s state-run media.
All six of North Korea’s previous nuclear tests have caused earthquakes with a magnitude of 4.3 or above.
But the series of quakes that have hit the region subsequently seem to suggest the detonations have dramatically destabilised the area.
Kim So-gu, head researcher at the Korea Seismological Institute, said: “The explosion from the Sept. 3 test had such power that the existing tunnels within the underground testing site might have caved in.
“I think the Punggye-ri region is now pretty saturated. If it goes ahead with another test in this area, it could risk radioactive pollution.”
Wang Naiyan, the former chairman of the China Nuclear Society, added: “Another test might cause the whole mountain to cave in on itself, leaving only a hole from which radiation could escape and drift across the region, including China.”
However despite the recent spike in seismic activity, the web journal suggests “complete abandonment of the test site as a whole remains unlikely”.
They said: “Such historical precedent, combined with the presence of two other, as yet unused tunnel complexes within the test site, leads us to conclude that there is no valid reason to assume that the Punggye-ri test site is unable to contain additional underground nuclear tests.”
And researchers will be keeping a close eye on the Punggye-ri site using satellite images of the region.