People in South Korea don't seem phased. It is as if they're used to these 'threats'. He has a lot of reasons to do what he is doing (consolidating power for instance), and I am sure he is well aware of the consequences of war, and that's why I don't think he intends to follow through on this.
But still ... I'm waiting to see what will happen on the founder's birthday next week.
Playstation = The Beast from the East
Sony + Nintendo = WIN! PS3 + PSV + PS4 + Wii U + 3DS