The concept of a nuclear winter is a discredited Cold War myth. Thousands of nuclear weapons were tested during the cold war and we're fine.I can't agree with the talk about nuclear war, that benefits no one.
Even if we assume a scenario, all along, China was spending at 3.5% gdp and had put the hidden budget into nuclear defense, kinetic mid course interceptor works perfectly and there's thousands in tunnel networks secretly built across the mainland. And now, China invokes "all warfare is based on deception" and revealed talks about nukes only being used for second strike was a bluff meant to enhance a first strike. The rocket force hits the US mainland with 1000 thermonuclear warheads, and then intercept every sporadic American return strike.
So after that, what will happen? The fallout from the nuclear strike will devastate global climate. Even if China was unscathed by second strikes, China's population will starve due to lack of global harvest. But not as badly as people in the third world would starve.
Any nuclear war even ones that end in complete "victory" will lead to all progress made by China to get wiped out and possibly even the end of human civilization.
Nuclear war can only be played as a dead man's hand, as die together option to deny the fascists from claiming global hegemony if the workers' conventional defense would ever fail. Death is preferable over nazi rule and imperialism. This has always been China's only stance towards nuclear use.
Americans have killed 30 million people since WW2, it's unlikely any changes to the climate will lead to a death toll anywhere close to that.