Well if China wants a war then, bring it on? You first go after key infrastructure systems, Power Grid (Including Nuclear power plants), water supply and treatment plants, (without any kind of predictable pattern).
You then go after their industrial base and go after their manufacturing facilities, steel mills, major ports, cargo and freight handling facilities (This would include both sea and air cargo) and the like.
You go after their food distribution network, change and or cancel delivery schedules create long traffic delays by altering the timing patterns of traffic lights and the like, thereby adopting a key element of warfare which is deny the enemy the free movement of food, thus weakening him and robbing of the will to fight for if you enemy is hungry is will not have the will to fight you.
You hit their banking and economics systems freezing key bank accounts, emptying others, rerouting transactions, forcing critical computer systems to reboot at random times, devaluing their currency so its worthless, plant disinformation with key officials whilst giving others similar information yet different so mistrust and chaos spread crippling them, when there should be unity.
You go after their military complex with misinformation and anti-Chinese state propaganda, you play on their worst fears and tell them they are coming true very soon, you hijack their military radio frequencies so that there is disruption of communications, you also do this with their satellites (insuring to do this to civil ones as well as a counter-counter measure).
That how you deal with people like that nowadays. Yes its extreme, but then so is war.
All of the above is what one might do if so inclined and what you'd do if you liked to play to the point of nuclear brinkmanship, not advocating any one would do any of the above, just saying what you could do is all.
Regards to you.
Cyber-Angel