That makes no sense, for a variety of treaty, telemetry, political, and foreign trade reasons. You don't launch missiles near population centers, even if in international waters, without notification and extensive Notice to Mariners pre-publication. You REALLY don't do something so bone-headed stupid right next to the biggest nuclear-armed power on the planet.
My bet is amateurs with an enhanced-contrail homebuilt rocket, looking for just the reaction they got in the first 12 hours. They may not like the reaction they get in the next 72 though.
lol - I don't know if I shall laugh or cry.
Obviously this is a missile launched by the US itself, there is no other nations interested in launching Inter continental ballistic missiles next to the US coast.
This is communication from the US, one of their many various ways of communicating their threats or comments to the world, or in this case to a part of it - specifically to Asia. The US did this all the time during the Cold war as well. If the US want to threaten Iran they can move some Carriers to the gulf, but that wont work on China because China has developed the Carrier killer DF-21D.
It can be compared with what Russia is doing now almost every day, the flying of Long range Nuclear Armed bombers up and down the US East coast, launched from their air bases in Venezuela.
There are many different things ongoing in Asia right now the US is upset about, and I assume you are intelligent enough to realize that this missile is launched by the US itself, despite the fact that they are lying about it.
the missile you mention is something like 20 or 30 years old, IIRC it was the first ballistic missile produced in China, guess that´s the reason I remember it. Why you call it carrier killer is beyond me.