I’ve been reading related articles on other sites. Seems like both the Turks and the Saudis want ISIS to grow large enough to take out Assad and act as a check against Iran and Hezbollah. In turn, the Saudis will drive down the price of oil so that Russia suffers. None of these players like the Kurds, they will be be thrown to the ISIS wolves.
Its like letting a cancer grow in hopes that it destroys a virus and then to fight the cancer afterwards. The corrupted minds produce illogic plans.