We have and have always had a plan for the Korean Pennisula. No need to make a plan when one already exists.
There is a difference between acknowledging an enemy of the United States and announcing specific military plans and the timing of moves against such enemy. Trump has made it clear he wont announce his military plans ahead of time. Our first taste of that was the surprise strike on Syria.
So, again, either this is more lies from the lying leftist media or Trump has more moles on his team he will have to root out.