"Separately, Turkish-backed groups have launched operations against largely Kurdish-held areas in northern Syria, which is in line with Ankara's long-communicated desire to move against Kurdish forces there and to control a swathe of land south of its border as a security buffer zone."
This seems Ottoman-dreaming Sunnis moving against Kurds (supposedly defended with US forces) and the joined Salafists, all wrapped against Shia mentality, and with a shared aim in the end -- targeting oil revenue (the practical) and Israel (the theological).
One learns: "....the Islamist group, Hayat Tahrir al-Sham (HTS)" is translated for us into "Organization for the Liberation of the Levant." In historical terms, that stretched from Turkey down to Egypt, and in modern terms still means Syria, Jordan and Israel.
One fine and complex mess, to be sure.