It's originally a Russian development. The technology was sold to Iran, which in turn sold it to China. It is a fearsome, ship-killing missile for which there is no available countermeasure.
It's called the Sunburn and is not new but has been around for several years. What makes it so dangerous is it flies faster than the speed of sound, carries an enormous payload (powerful enough to sink a carrier) and it follows a sensor-maintained flight path no higher than six feet above the surface of the water, which makes it undetectable by conventional radar. And it costs less than a low-grade fighter plane to produce.
We'd better hope that a countermeasure for this weapon is developed soon, because it conceivably could render our Naval warfare capability totally useless.
I'm sure there is a countermeasure, the missile has been around for a while. and this is different then the balistic missile quoted in the OP's message.
these missiles can still be shot down by AA missiles, it is just harder to do it. There are also additonal countermeasures, such as shooting down the launching aircraft, sinking the launching boat, or even creating large water plumes in the flight path of the missile.
Add in all the ECM/chaff/ etc countermeasures and the weapon is still a far cry from one shot one kill.
if it comes in like an Exocet which is not what was described in the op as you noted, yes we have counter measures, we have point defenses etc. that have been upgraded since say, the Falklands. I would think we studied that and fly our CAP further out than 30 miles and use side scan and underneath the envelope radar etc.
IF its a high flyer plunger, vectoring in a missile from 100K feet up, on to a surface moving at 30 knots,even at what appears to be a huge 1000 feet long and 200 feet wide is not as easy as it sounds. They'd need constant surveillance, interference free communications between the 'driver' all the way to the missile until it acquired the target, then of course we would attempt to jam its on-board homing devices.
Its size as in carrying a payload that could "kill" a carrier is a virtue in that its purportedly a one shot one kill, but the size required to make it so, means less maneuverability especially when its goes 'terminal' on its final flight path etc.
In 2008, an Aegis launched SM-3 intercepted and 'killed ' a decaying U.S. satellite re-entering the atmosphere at over 20,000 mph. Apparently we aren't asleep.