Todays's 'South China Morning Post,' has the Headline:
North Korea’s nuclear test site has collapsed ... and that may be why Kim Jong-un suspended tests
The mountain’s collapse after a fifth blast last fall has led to the creation of a massive ‘chimney’ that could leak radioactive fallout into the air, researchers have found.
Full report at: http://www.scmp.com/news/china/diplomacy-defence/article/2143171/north-koreas-nuclear-test-site-has-collapsed-and-may-be-why-kim-jong-un?utm_source=emarsys&utm_medium=email&utm_content=20180426&utm_campaign=scmp_today&aid=190131336&sc_src=email_2221295&sc_llid=54531&sc_lid=151076047&sc_uid=z7Rq3JwHwQ&utm_source=emarsys&utm_medium=email
I guess its a reasonable question that the SCMP then asks, whether that's the reason for Kim Jong-un's sudden reversal of policy?
The SCMP also points out that the 'chimney' formed by the mountain's collapse may be releasing radioactive substances into the air.
Not a very desirable thing to happen.