China, or any country in this scenario is by definition attacking the US using Weapons of Mass Destruction aka WMDs. The default upon usage of WMDs against the US is to respond in kind. That means a massive nuke counter strike sending the adversary back to the Stone Age.
Question... Would a D President (ex. Biden/Harris) have the cahones to do this or wimp out?
Cajones.
A modern Democrat pres probably wouldn’t be able to locate the nuclear football or the nuclear codes judging from their history.
Re Cajones:
Against a democrat ally, the ChiComs? No.
Against our own people, yes.