A gesture and nothing more. I read in the early reports of the missile strike that the administration notified regional allies and some regional news outlets beforehand. If true, I suspect it was to allow the Russians and/or Syrians to get their aircraft clear of the runway, the designated target.

So, an expensive gesture intended to wow the Trump base, placate the hawks, and prove to Trump that he is a more manly president than Obama, who wouldn't cross that "red line". Mission accomplished! And it only cost 90 million or so, which is 60% of the annual budget of the National Endowment for the Arts, which Trump is eliminating to save money he'll spend on tax breaks for billionaires, and a few new aircraft carriers and nuclear submarines.