The Chinese will attack the US when they detect the US (and that includes being given a link). The US will attack once they are attacked.
You can simulate driving someone off with pinging using an approach trigger set to an "intimidating" range (say 5nmi) combined with a doctrine that tests for the target's detection of your active sonar. Couple that trigger with a script that changes the target's course to one that leads it out of the area and a change the speed to a reasonable transit speed.
To edit a campaign mission, just find the command "load campaign mission" in the drop-down menu (probably File).
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