The Kurdish crisis requires some explanation. First, the idea of Nationalism began in Western Europe, then spread to other areas, slowly. Eventually it reached the Middle East during the last stage of the Ottoman Empire. It penetrated the Greeks of Ionia, the Armenians, the Kurds, and the Arabs.
Just as the body’s immune system generates resistance to dangers, so did Nationalism among the subject peoples of the Ottoman Empire generate Nationalism among the Turks. Horrific things followed. In brief compass, the Ottoman Turks drove out the Armenians during the First World War, and the revolutionary Turkish Republic slaughtered large numbers of Greek Christians. Regardless of whether these were acts of “genocide,” a ton of Greeks and Armenians died as a result of Turkish government action. (Certainly, lots of Greek soldiers deserved to die for their actions in Turkey, but most of them got away to ships for home, while the civilian population was abandoned to the revenge-minded Turks.) However, many Kurds remained within the boundaries of modern Turkey.
Second, when the George W. Bush administration decided to attack Iraq in 2003 for no good reason, one effect was to fracture the country into its component parts. A Shi’a Arab majority in the east opposed a Sunni Arab minority in the west and the Kurds in the northern part of the country. Us liking it or not, the Iraqi Kurds saw their self-governing territory as the core of a united Kurdistan. The projected Kurdistan would include Turkish Kurdistan, Iraqi Kurdistan, Syrian Kurdistan, and even Iranian Kurdistan. So, Kurdistan has many enemies and few friends. OTOH, “neither are they afflicted by the disease of indecision.”
Third, when ISIS attacked out of eastern Syria and over-ran much of Iraq, the armies of Iraq and Syria were rotted by corruption and civil war. The US faced a choice: leave it to Turkey, Iran, and–needs be–Israel to solve the ISIS problem OR thrust ourselves back into regional affairs. The Obama administration chose a partial re-engagement. Send Special Forces troops as trainers and target-spotters and send US air power. The real heavy lifting would be done by an “Arab” army of mostly Kurds, with an icing-on-the-cake of “moderate” Arabs.
Fourth, basically this worked OK. Not perfect, but OK. Now we’re faced with the question of how to get out of the “Forever War.” What do we owe to the Kurds, who have been fighting for their own nationalist interests? What do we owe to Turkey, a NATO ally with a large and restive Kurdish population? What do we owe to ourselves, to our self-image? “You dance with the girl you brung,” my Dad always said.
Fifth, Russia gets Syria? So what? The place is a ruin. The Russians already have alliances with Iran, the Shi’ites in Iraq, and the Alewites of Syria. All formed under the Obama Administration. Turkey has already bolted on NATO. Much of that seems to be on the watch of the Obama administration. Focus on the essentials of American interests: oil from Saudi Arabia; and–more importantly–the Far East.
 I’ll leave aside all the BS that has been talked about of late about Patriotism as “the love of one’s own country” versus Nationalism as “the hatred of other countries.”
 See: Smyrna.
 See: “”In Harm’s Way.” https://www.youtube.com/watch?v=yXzNQHNsQHk