https://theconservativetreehouse.com/2018/12/24/president-trump-and-turkish-president-recep-erdogan-this-should-be-interesting/#more-158096

The announcement of The United States drawing down troop deployment from Northern Syria – with the United Arab Emirates, and Saudi Arabia sending in replacements to bolster the region, highlights a much larger backstory.

Very good article laying out a sequence of events, connecting a lot of dots, and bringing us to events of today.