The US is NOT obligated to protect the Turks from any consequences of their invasion of a sovereign neighboring nation (Syria). Should the Syrian ally Russia bomb the invading Turkish forces, WE SHOULD NOT HELP EXTRICATE THE TURKS FROM THEIR FOLLY & their illegal invasion. Let them suffer their own casualties & retreat from Syria back into Turkey. The Kurds, with American help, will complete the defeat of ISIS with which they have been successfully engaging.
Problem.
Erdogan is insane with ego and illusions of greatness. Very dangerous disease for an Islamist to have.