@blatham,
I agree with Waldman although I never thought I would ever write those words.
Some may or may not know that I have for years expressed the position that Rules of War are obscene because they work to make war more acceptable.
Chemical weapons are only more heinous than conventional weapons because their use suggests that the carefully laid out Rules may not hold. (Of course there is also the fact that they may be easier to deploy in a civilian center than conventional weapons).
If any bad actor is allowed to get away with the use of chemical weapons, it inevitably opens the door for others.
I'm sure Trump was moved by the photos he saw. The man is not a monster despite the hyperbolic idiocy of some of his critics, but the primary reasons for the US strike do not include avenging slain babies.