If you read more about the many combatants in syria you will see the Kurds are leading with the most to gain and the most success against daesh. The Kurds were cut out of land allocations when the British Empire vacated the area. Post Colonial Wars are still being waged. And the U.S. Commander in Chief just tossed in a thousand plus Marines and Rangers in country with heavy artillery facing four other armies in the region, two of which they have no clear rules of engagement. Who knew the Middle East was so complicated?