https://www.nationalreview.com/2019/10/trump-used-the-options-he-had-in-syria/
There was no reason to leave a few Special Forces in the middle of an armed conflict when, yes, Erdogan might be willing to risk war with the U.S.
There has been a great deal of outrage expressed over the fact that the United States did not prevent Turkey from initiating the military operation to create a “buffer zone” in northern Syria. The major objection seems to be that in withdrawing the 100 or so American Special Operations forces who had been stationed in the area, the United States was giving permission for the operation and abandoning the Kurds who have helped us in the fight against ISIS.
I don’t see the criticism; in fact, far from abandoning the Kurds, the United States has consistently opposed the Turkish buffer-zone operation and used every means to prevent it that were consistent with America’s overriding national interests in the region.
The Kurds are tough fighters and were indispensable in supplying the ground component against ISIS. They had their own reasons for doing it, of course. Apart from not wanting to become victims of ISIS themselves, the Kurds are a stateless people and they have been trying to carve out a self-governing enclave for themselves in Syria or Iraq or Turkey or wherever they can get it. The success of the war against ISIS, and the prominent role of the Kurds in the effort, raised at least the prospect of such an enclave in northern Syria.
The United States does not support Kurdish separatism in Syria, but the Trump administration did try for months to get Turkey to agree to joint patrols and shared control in northern Syria; the purpose was to prevent further conflict and instability in the region, enable a continued focus on the fight against ISIS, and ensure effective security over captured ISIS soldiers. But it would have been at least a small step toward Kurdish autonomy.
Recep Erdogan was impatient, to say the least, with the American negotiating position. Erdogan is no fool, and he was aware that the Kurds were developing a significant measure of de facto control in northern Syria. Turkey and the Kurds have a long and checkered history, and Erdogan is as opposed to Kurdish separatism and statehood as the Kurds are in favor of it.