(I wrote this on October 6th while on vacation in anticipation of trouble from North Korea)
The Norks are going to piss off somebody, but it probably won't be the American Opposition. All they care is that they can snipe at the President's foreign policy. Apparently they are pissing off the Japanese. And why shouldn't they. Korea isn't far from Japan and a new nuclear neighbor is not needed when those nukes are in the hands of a government and people as desparate as the North Koreans.
I don't have nearly enough information to recommend with much gusto, the escalation of the military preparedness of Japan, but I trust them. What I trust about Japan is what I trust about what I've learned about their culture and for what business dealings I have had with Japanese corporations. In some important ways, it can be boiled down to the archtype of Japanese decision-making. Japanese come to consensus and agree upon a plan of action, it is dishonorable to stray from that consensus. and they will risk the sucess of a project in order to honor that consensus. Japanese decision making is risk-averse but their organizational discipline is admirable.