It absolutely warrants a response.
But let me remind you that we bombed Syria last year, and it had zero impact on the big picture and- especially- in deterring the use of chemical weapons.
There are other options, and that's why everyone has been trying to talk him out of this. That tweet he sent was just another example of why he is abjectly unfit for this. He makes rash decision, his own self-interest is his only preoccupation, and the usual checks and balances are intentionally failing.