It seems Trump's head of military has resigned following Trump's decision to leave Syria (we have been told Trump falsely believes ISIS has been defeated).

There are many ways to interpret the situation in north east Syria.
1)The oil fields east of the Euphrates are providing no revenue streams to Assad's government (Assad incidentally is the legally elected President of the country) THe oil is being sold illegally.
2)Within this   area The Kurds are fighting for an independent territory, while fighting ISIS. US troops are embedded with the Kurds.
3)Turkey will not countenance a Kurdish territory carved out of Turkey and Syria.
4)Russia has moved their lates generation air defence system in Syria and declared a legal no fly zone. Coalition and Israeli planes are now at risk of being shot down, especially after the accidental downing of A Eussian plane recently, that resulted in multiple deaths.
5)If Russia controls the airspace and Erdogan goes after the Kurds(as he intends to), US troops are in the firing line with no air defence.
6)Captain sensible would packhis bags and depart before all hell breaks loose.
7) It also needs pointing out that Russia in an invited ally in Syria. US troops are invaders with absolutely no legal basis to justify their presence.