I think a provocation that intends to produce some type of standoff, draws additional US military assets into the theater, with the intentional of exploiting any riffs this may create.
Most Japanese believe that the SDForces have the right to respond to, but not initiate war. Such an act of agression would result in some type of Japanese reponse (they have some surprising capabilities), but most likely would result in a blockade of everything but humanitarian aid, the freezing of all N. Korean assets, (which are considerable in Japanese banks), and some right wing rhetoric. (which the Koreans would try to exploit).