Why has North Korea chosen NOW to threaten the USA or South Korea?  Scriptures have made it clear that G-d is going to leave mankind without excuse on judgement day, and this may be part of it.  Iran is threatening to nuke Israel into oblivion.  North Korea is threatening to nuke the USA into oblivion.  But the leaders of countries that support Iran but not North Korea will be left "without excuse" on judgement day when G-d calls them on why they supported sanctions against one but not the other.  G-d could depose Kim Jung-un if He wanted to, but he uses everything for His purposes, including the wicked, one way or another.  Sometimes He allows evil to happen in order for it to be exposed.

Shalom, Joe