I think Trump got this one just right. He did not go so far to change the military situation on the ground which would need direct military invention by the US  with no guaranty for a better outcome for whole of Syria and it's people. But he did sent a stern warning against the introduction of a new weapon into the destruction scenario played out there. It puts the ball now into Assad s court and wait for his reaction before having to make another decision. I am aware that ultimately being killed, maimed, and burned by conventional used munitions is just as gruesome and horrific as chemical weapons but the use of the latter introduces just another unpredictable scenario of death and  apocalyptic destruction visited on to the victims modern warfare.