In 1967 Kim Il Song began what (I believe) was called "Juche" -- taking the South by force preceded by revolt against the ROK government. From then until 1971 the North launched many attacks against the ROK, including the Blue House Raid, the Pueblo, and the shoot-down of an EC121 "spy plane". The attacks lessened after that but still continued.

During this time the US and South Korea were involved in Vietnam. DPRK is again pushing when the US is involved in combat elsewhere (Afghanistan, Iraq). Militarily, DPRK and ROK are pretty well matched militarily and many believe that ROK has or could very quickly develop nuclear weapons (the US removed all of theirs in 1991 but can fly them from Guam or Okinawa within a couple or three hours).

Park Chung He, the President of ROK in the 1960s, was quite ready to head North, especially after the Blue House Raid.

If provoked ROK will fight back and the US will assist due to treaties signed many years ago (and the troops would shoot in self defense in any case).

Except for Kim Jong Il being in very bad health and an internal power struggle going on inside DPRK I would expect the same-o, same-o as in the past.

Because of the internal struggles I would not be surprised by a war.

I only wonder what will happen when the NK troops get a look at the life style and economic prosperity in the South. Will they realize the lies they've been fed?