It's not about China. It's about the military doing it's job, which is the enforcement of political policy by means of violence. There is a broad spectrum of possible responses to an attack ranging from "ignore it" to "nuke it". Computers don't change that.

A more direct answer might be this: What if an enemy hacker was attempting to compromise battle plans for an impending invasion? I suspect the military would try to stop that effort with violence if there were no easier way.