We're spying on them, of course they're going to follow us. What would you expect if Chinese surveillance aircraft were flying 50 miles off our coast? Would you expect the USAF not to tail them too?!?
Of course.
My point is that the average clueless American buying cheesy ChiCom patio furniture at WalMart doesn't have a clue about the military chess game that is going on off Taiwan.
But they will soon enough.
We intercept all the time.
What the chinese did was cross an understood boundry in pursuit. . .that is a hostile act.