What will happen to Syria's Kurds once American forces pull out of eastern Syria? Actors involved don't agree:
There is no agreement (between the major powers with forces in Syria) about what to do with the Syrian Kurds and their SDF militia, which was largely responsible for destroying ISIL (Islamic State in Iraq and the Levant) in Syria, including capturing their capital city Raqqa. There is a conundrum about how to handle the Kurds/SDF. It goes like this;
The Syrian Kurds want an autonomous Kurdish region in the northeast, similar to what the Iraqi Kurds have had (for 25 years) next door in Iraq. The Assads are inclined to allow that (as the Assads have been able to work with the SDF for years even though the SDF are technically Syrian rebels). The Turks and Iranians oppose the Kurdish autonomous region while the Russians and Americans support it.
In one sense, America's withdrawal only accelerates rather than causes this issue. Even if 2,000 American troops stayed in eastern Syria, eventually Syria will recover enough military power to attempt to retake eastern Syria. Or Assad's forces would recover enough to inflict a Beirut Barracks-style terror attack on our forces there.
I once thought we might have gotten a de facto autonomous zone we could patrol along the deconfliction line (the DCL, as I eventually called it). But without Assad's cooperation, we'd need a major force to defend it. Assad would probably agree to this as would the Kurds. But Iran and Turkey--who both have restive Kurdish minorities--are opposed. Remember that in 2017 Iraq's Kurds got slapped down by Iranian-inspired Iraqi attacks that rolled back Kurdish controlled territory in Iraq.
That's why I said we had to decide what our objective for being in Syria was before some Beirut-style mass-casualty attack took place. Remember, Iran was behind that terror attack. Do you really think Iran wouldn't try to do the same thing to American troops in eastern Syria? We really haven't decided on an objective we can achieve and what the American people would support at the price of significant casualties; and so yes, it makes sense to pull our troops out of Syria. But we really need to do something to bolster the Kurds who helped us defeat ISIL even though in the long run we can't save them from Assad's wrath if he chooses to strike back.
Nobody has any stomach left to continue to oppose Assad to the point of overthrowing his minority Alawite regime even though his military power is largely spent from the multi-war, and he relies on Iran's power (money, expertise, Hezbollah, and a Shia foreign legion) and Russia. The British and French will pull their troops out of eastern Syria, too (as that initial Strategypage post reports--unless our decision to keep 200 troops there "for a period of time" convinces them to remain a bit longer), despite the fact that they have more interest in Syria than we do because of Syria's role in pushing so many refugees/migrants into Europe over the last half decade.
And it would be very hard to reconstitute armed rebellion after letting the non-jihadi rebels wither on the vine and finally die. Remember, the Kurds were never going to be the core of an anti-Assad force willing to march on Damascus.
This is why I wanted a focus on Assad in Syria before going after ISIL in Syria. My idea was "win, build, win" of defeating ISIL in Iraq while building up non-jihadi and non-Kurdish rebels in Syria; then after defeating ISIL in Iraq turn to winning against ISIL in Syria.
After that, because we had built up new rebels in the east and continued to support rebels in the west, we could go after Assad.
Of course, Russian intervention in 2015 to bolster Assad ended the hope of that kind of plan. The very length of time it took America to help Iraq defeat ISIL combined with our effort against ISIL in Syria which was essentially a gift to Assad may have given Russia the opportunity to intervene.
So here we are with Assad still in the throne after we struck weak blows against him; the Syrian Kurds who helped us defeat the ISIL caliphate are exposed to Assad and Turkey; and no objective we could achieve with a small force absent an agreement that recognizes the situation on the ground. Even a small American contingent with allies in support only buys time to figure out what exactly we want to do in Syria.
And Iran thwarts an effort to resolve this Kurdish problem. Iran really is a Gordian Knot for resolving a lot of problems in the Middle East.
UPDATE: The small American presence in the north and south could very well encourage European allies to retain troops there.
Indeed, it makes little sense for us to keep that small number of troops in Syria unless our allies remain, too, backed by our air power.
