Japan's defense minister has ordered missile units to intercept the rocket if it or its fragments threaten to hit Japan. Seoul has also warned it might shoot down any parts of the North Korean rocket heading for South Korean territory.
It could be just a coincidence, however the threatened rocket launch by North Korea will force the Obama Administration to split their attention between the Middle East and the Pacific. Most the US fleet is trying to face down Russia and Iran in the Middle East and are out of position to influence much in the Pacific. The new North Korean leader may be trying to assert himself on the international scene or simply is following in his father and grandfather's footsteps in flexing North Korean military muscle (while their population gets hand-outs for the US).