To be fair, Trump isn’t the only President to have blundered over Syria. Obama created much of the mess.
Fearing America being drawn into another Iraq, the US decided to bring down Assad in Syria using a proxy army of Syrian Rebels. They gave them loads of money, equipment and intell. Unfortunately they were mainly ISIS fighters and their aim was to create a Caliphate.
When it dawned on the US that they had created a monster, the enlisted the Syrian Kurds whose motives were territorial and nationalistic, rather than fanatical religious nuttery. The Kurds stopped, and then defeated ISIS.
Barely had the present POTUS tweeted his joy (and taken the credit for ISIS’s defeat) then he decided it would be a good vote winner to bring the US troops home.
Turkey, long time enemy of the Kurds could not believe their luck at such a stupid mistake by Trump, and they set about attacking the Kurds with indecent haste.
For America it’s a clear instance of snatching defeat from the jaws of victory. They are now being humiliated by Turkey. ISIS can reform. They have spent $Billions and Assad is more powerful than ever. And suddenly America looks weak and dishonourable.