My sense at the moment is they are pursuing a "humiliation" strategy where they will persuade Trump to withdraw by making it too embarrassing to continue. For that, all they have to do is make him look impotent, which they achieve by continuously provoking just enough to force a response (either military, or Trump to issue yet another TACO threat he can't carry through with) but then popping up a few days later with a new attack showing it didn't work.