Thats what chinese state media says. Doesnt mean that its true.
I feel the denial is strong with this one...
Chinese state media officially announcing it is about as explicit and definitive as one can ever expect China to be on military affairs.
If that isn't good enough for you, nothing will be short of China sinking a carrier with such a missile in a war.
If any country starts doing that, it runs a serious risk of nuclear retaliation. No power will tolerate destroying its strategic weapons eyes.
China has a no first use nuclear policy, where it explicitly states it will only use nuclear weapons as a retaliatory weapon after it has been attacked with nukes first.
That is why it is keen to develop credible deterrence in all other military realms, be it space or cyberspace, so it could effectively deter potential enemies from attacking China in those realms without having to keep going back to threatening the use of nukes.
If anything, threatening nuclear retaliation for non-nuclear first strike attacks is an empty bluff against a fellow member of the nuclear club.
To draw such a line in the sand is to invite others to step over it and make you back down, because no one would be stupid or suicidal enough to follow through with such a threat knowing enemy nuclear retaliation is sure to result if you do.
The only exceptions I can think of are if one side started to systematically target the strategic nuclear forces of another nuclear state with conventional forces, thereby placing said power in an "use them or loose them" dilemma, or if someone launched a conventional attack against civilian targets designed to cause nuclear strike levels of devastation.
Things like bombing damns to unleash devastating floods that kills vast numbers of civilians or striking nuclear power plants to unleash clouds of radiation etc.
Such atrocities would probably force China to reverse its no first use policy, but that is someone pretty much going out of their way into provoking China to do so.