That's what the world did with Hitler, looked the other way.
In what universe is Assad reasonably like Hitler? I swear...the whole “look what Hitler did!” line has been used to justify intervention within every nook and cranny of this planet.
I get it. Chemical weapons being lobbed at civilians is a terrible thing. But there are people starving in Africa. There are narcos butchering each other in Central America. There are trees falling in the forest. It just isn't on us to fix everything. Not only is it against our founding principles, but it is impossible.