From what I have read, the DF-21 will be dependent on guidance for both ground and sea based tracking. Otherwise they would be packing an awful lot of systems into a warhead.
The DF-21 carrier missile may resemble a Pershing missile.
The US Navy has been facing this type of threat for years. Anti-ship missiles are nothing new, especially missiles that are dependent on external guidance (such as an aircraft or ship to illuminate the target)
The threat is real, but what is more of a threat is our determination to water down our military capability to the point if a shooting war comes, our personnel, equipment readiness, technology and training will be inadequate, and people will die.
Or current administration and Democrat party is more interested in turkey basters for lesbians and bailing out unions than it is in providing funds to develop, deploy and use advanced ASW assets.
If a shooting war comes, and our military and the systems used are incapable of meeting the threat, there won’t be time to “catch up”.