The problem with the Iraq comparison is that the US was hell bent on attacking Iraq and was looking to manufacture a pretext. That's not the case here. 

Perhaps more dangerously, the US strike shows the unpredictability of the Trump administration; a week ago, senior administration officials, and the President himself, were essentially saying that Assad wasn't their problem and that it was up to the Syrian people to work out what happens (yeah right!). Understandably, the Assad regime understood those comments to mean that they had a free hand to do what they would. That's why the gas attack happened. 

I'm sure nobody was as surprised as Assad by the about face and, even though the attack was largely theatre, the Assad regime and the Russians must be wondering what's next. I expect the message from the attack is meant to communicate to the Assad regime that it is free to exterminate Syrians using conventional means but that it must refrain from using chemical weapons.