At least that is what this Stars & Stripes report says:
Amid concerns that North Korea could be preparing to launch on if its new missiles, Pentagon officials told the New York Times that it could calculate the missile’s trajectory within seconds and attempt to to shoot it down if threatened South Korea, Japan or Guam, an American territory. However, if the missile was headed for the open sea, even if flew over Japan in the process, military action would not be taken, the Times reported. [Stars & Stripes]
I had been wondering what the response would be if a missile was fired over Japan because if you look at the geography the Musudan would have to fly over either Japan or Korea to test its maximum range. It appears the Pentagon has given the North Koreans the green light to fire over Japan. I wonder if the Japanese are on the same page with this?
I would not be surprised if the North Korean if they do in fact fire a missile over Japan than claim that their missile technology is so advanced that they defeated US and Japanese missile defense systems.