well i remember reading somewhere Turkey did offer to send in troops to combat ISIS if the US supported it but obviously it would be considered an unlawful invasion. And can you really blame them for taking their borders into control when a civil war has went on for 10 years. Imo currently the best outcome has happened, the worst being syrian kurds claiming a new kurdish state because that would absolutely de-stabilize the region further. It would lead to Assad with Russian backing vs seperatist Kurds with US backing (possibly). Of course i sympathize with the kurds but as it is their ambitions and goals were unrealistic and every country in that region will oppose them.