I am more cynical. I think using cruise missiles on Assad was collaborative effort with Russia. Putin lost control of Assad and this is a step to bring him back in line. You might think poorly about Russians, but chemical weapon use is a big No-No for them. Russians finished decommissioning their own arsenal in 2016.

Why I think this was coordinated with Putin. First, Russians were given advanced warning and they chose not to activate AA defenses. Second, US used old missiles that were likely to be replaced by new tech. Third, Assad embarrassed Russians who guaranteed his compliance in 2013.