I'm not a war hawk, nor am I a fan of military intervention and putting US troops in danger, but I'm also a pragmatist. Turkey and Syria would not be making these aggressive actions if they didn't have assurances and backing from Russia. Russia's recent moves in the middle East are pretty alarming, since they seem to be goading the likes of Iran, Turkey and Syria in order to increase their sphere of influence in the Middle East. Turkey already has nuclear weapons of their own, plus the nuclear weapons NATO has over there. Iran has nuclear ambitions of their own, and are being bankrolled by Russia. Once nuclear weapons proliferate into the likes of Iran and Syria, it'll be game over, because the Islamist elements of those governments have no qualms about using nukes in their religious jihad bullshit.
As for the Kurds, they're were one of the few allies the US had in the middle East, and were vital in the US curbing ISIS. The fact that we're essentially abandoning them to be slaughtered by the Turks means that we'll have one less ally in the Middle East to prevent the ambitions of Russia and the containment of Islamic jihad.