Syrian army advances in northwest Syria are putting Turkish troops in the firing line and threaten Ankara's hopes of preventing a new wave of refugees on its southern border. The offensive around Idlib, the last major rebel stronghold in Syria, has already forced tens of thousands of civilians to flee towards Turkey. It has also cut off a Turkish military post deep inside Syria as the deal to limit fighting in the region, which the Turkish troops were supposed to be monitoring, collapses. The breakdown of that deal would be a significant blow to President Tayyip Erdogan, who has steered...