This is a Classic Case of Deterrence

It appears that the Chinese DF-21 anti-ship ballistic missile is operational, a 900 mile range anti-ship missile, at least according to Admiral Robert Willard, Commander, U.S. Pacific Command.

It's intended to be a carrier killer, and while the capabilities, particularly the targeting, are unclear, but considering that the Pershing II's MARV (MAneuverable Reentry Vehicle) got a roughly 30 m CEP, it will certainly give a CVBG cause to pause.

Even the warhead is nothing more than 150kg of high strength steel descending at 1000 m/s, it will still completely ruing a carrier skipper's day.

There are 2 possibility two possibilities here, either this is an attempt by the Pentagon to hype the Chinese threat, or the Chinese are trying to create an effective no-go zone for the flat-tops by creating uncertainty steps to cut in the missile in an operational posture.

Then again, it might be both.