The HTC and the SDF have been cooperating for years. Both of them tolerate the Turkish interference in northern Syria. HTC can use the US military presence as a temporary means of reducing internal Syrian tensions. Allowing the Turkish military and Turk funded militias to stir up chaos in the north of Syria is not positive towards establishing a new Syrian government and economy that will take years to evolve. Essentially the peninsula nations are quite relieved to eventually have the Turks and Iranians out of their hair.