TEN YEARS AGO, IT APPEARED TO BE THE beginning of the end for Syrian President Bashar al-Assad. His government’s brutal crackdowns on peaceful protests in 2011 had given birth to an insurgency backed by foreign foes—the U.S. among them. Atrocities mounted, including use of chemical weapons against civilians, mass murders and torture, over the course of the decade-long civil war that followed. Estimates suggest that more than 600,000 people have died and millions more have been displaced, making the Syrian civil war one of the deadliest, most disruptive conflicts of the 21st century.
One by one, countries severed ties with Assad and his government, including the U.S., which imposed economic sanctions in 2011 and shuttered its embassy for good in 2012. Even the Arab League, an influential organization of fellow…