How do you accidentally fire a missile into another country? When North Korea does these things, they are on purpose.
In any event, to use a morose term, I hope their postmortem results in making sure it's not possible to fire into another country accidentally.
You can't accidentally fire a nuclear missile and have it go off.
The Soviet nukes left over in Ukraine, Belarus and Kazakhstan were protected.
There are, IIRC, several nuclear weapons related accidents where the warheads were recovered by the reports, to the extent declassified, do not indicate that all safety mechanisms worked as designed. I would not assume from the fact that weapons are typically designed with the intent to prevent accidental nuclear detonation and so far the accidents that have occurred have not resulted in accidental detonation that such is categorically impossible.
https://news.google.com/newspapers?id=g5lVAAAAIBAJ&sjid=MkAN...