On Saturday, the geopolitical world was shocked when Turkey began shelling Aleppo, where the Syrian opposition has its back against the wall in the face of an aggressive advance by Hezbollah and the IRGC supported, of course, by Russian airstrikes. To be sure, everyone knew Ankara and Riyadh would have to do something quick if they wanted to preserve the rebellion. Their proxies are being rolled up rapidly by Hassan Nasrallah's army and Vladimir Putin's air force juggernaut. But few expected the escalation would come so quickly. But Recep Tayyip Erdogan is unpredictable (just ask the lone surviving pilot of...