Chaos and horrors followed President Trump’s needlessly abrupt withdrawal of US forces from northern Syria, but much of the mess was baked in long before Trump ever took office. In other words, this president played the anti-ISIS hand that the last president had left him: An American exit was always in the cards, and all the players are falling into positions prompted by Obama-era US policy. Thus the Syrian Kurds have allied with bloody Bashar al-Assad in the face of the Turkish invasion. This is less strange when you realize that the Obama administration chose the Kurds as its anti-ISIS...