For now, Turkey is conducting a restrained campaign to strike Kurdish militants in Syria. But cycles of retaliation between its troops and the Syrian Democratic Forces (SDF) could spark a new, major Turkish invasion, which would complicate ties between Ankara and Moscow, push the SDF closer to Damascus and possibly end the SDF's alliance with the United States. On Aug. 16, local observers reported heavy fighting between SDF and Turkish forces near the northern Syrian city of Kobane, which lies in between two Turkish buffer zones and also hosts some Syrian government troops. Several Turkish drone strikes have also killed at least three SDF commanders in the past month. Meanwhile, the SDF has been striking Turkish forces both in Syria and Turkey itself, as the SDF attempts to deter further Turkish operations against the group....