In my view Trump had a somewhat different reality check here. Put simply, Trump made a mistake. His administration’s comments last week supportive of Assad made Assad believe Trump was on his side. Feeling that he had both Trump and Putin on his side, Assad believed Trump would not care about the chemical attack.
Why wouldn’t he believe that? Not only did the Trump administration make the supportive comments last week, but Trump previously strongly condemned Obama for wanting to strike Syria because of chemical attacks on its people.
Quite clearly Assad misinterpreted the Trump Administration’s comments last week. However, Trump was in the position of having to correct his own blunder in making Assad feel secure about using chemical weapons. So this attack was really about Trump fixing his own diplomatic bumbling.
It was also about undermining the investigations into “Russia-gate.” The core concern associated with that investigation is that the President of the United States might be overly chummy with Russia and its strongman leader. What better way to neuter that concern than to attack a Russian ally? What better way to get the news reports of increasing evidence of Trump associate ties with Russians out of the news cycle than launching a few score cruise missiles?