Today Syria is held out as Iran’s “Airstrip One” in the Arab World—an Orwellian island Tehran uses to project its power to Israel’s borders and the shores of the Mediterranean. Indeed, Iranian-Syrian relations seem closer than ever—including a newly signed military cooperation agreement. Ties between Damascus and Tehran deepened over the last two years in the face of US and Western isolation, helping their support for militant groups Hezbollah, Hamas, and Islamic Jihad crystallize into an “Axis of Resistance” against Israel and the United States.But...