Sooner or later, al-Qaeda, Islamic State or the next iteration of jihad will break loose in Syria. When that happens, the Russians will be the new Satan on the block. Their diplomats in Damascus will come under attack, as will Russian troops. More troops will be sent to defend them. Putin’s much-prized Mediterranean naval installations will require reinforcement. And so on. Soon enough, jihad will inflame Russia’s large Muslim population. Moscow itself will become a terrorist target.
The “safety zone” that Putin and Turkish President Recep Tayyip Erdogan have recently carved from northern Syria will collapse. Syrian leader Bashar al-Assad rightly considers it a violation of his country’s sovereignty, and if he can persuade his Russian patrons to shut down the zone, Erdogan will threaten another invasion. If Putin then sides with Turkey, Assad will take matters into his own hands. His army may not be fit for fighting armed opponents, but the Kurds are and can act as Assad’s proxies.
If and when such a border fight develops, Putin will find himself between Assad and Erdogan. Whatever he does, he will wind up in that most vulnerable of Middle Eastern positions, the friend of somebody’s enemy.