You are all operating on the basis of a groundless myth. If that was a missile, it corresponds to an SLBM launched from a submarine on a northbound trajectory from Puget Sound. I have analyzed this photo, from where it was taken and the azimuth of view. So, it was going in a much different direction than Hawaii, and such missiles are not intended for nor capable of intercepting aircraft. My surmise was that it may have been an attempt to provoke a strategic incident with Russia. (There are no anti-aircraft systems that have the range or guidance to engage an aircraft over the Pacific from the Puget Sound.)

Why/how was it shot down? Because Bangor, WA is the western home port for ballistic missile submarines, McChord Air Force Base is close at hand, and this may reveal that the DoD has a fail-safe policy of keeping the sub base under constant patrol to counter exactly this kind of event, be it sabotage or accident. An air-to-boost-phase interceptor missile is well within current technology and might be a very secret capability. Thus, whitewash, forget, and maintain the secret.