There were not fooled. Trump pisses on you and laughs watching his election campaign speeches.
There's another possibility that you're not seeing, the media is easily fooled and this strike that did so little damage to one airfield was done to placate the war hawks in this country and the populace that is horrified by the gas attack to show the public that our current government is "doing something" to retaliate against the supposed perpetrator. Basically a PR move with the Russians and Syrians knowing full well in advance and with their agreement to make it look like we're "punishing the bad guys". The only thing we may have hit were old hangers, bunkers and junk planes that were left there specifically for that reason, I mean come on, those cruise missiles are pretty accurate.
Given that and the possibility that we may have already known Assad wasn't behind that attack but that the American people would never support our government backing Assad it was allowed by the Russian and Assad so we could maintain the American populace illusion of siding with the "freedom" fighters.
In other word, politics.