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For the majority of Arabs, Syria symbolizes all that is wrong with Iranian influence in the Middle East. Since 2011, Tehran and its regional proxies have poured men, money, and weapons into Syria to prevent President Bashar al-Assad’s military defeat. In June 2013, Hezbollah’s intervention in the western city of Qusayr single-handedly turned the tide of the war in Assad’s favor.

Iran’s stakes in Syria are high. Three overriding priorities drive its policy: to defend Hezbollah’s weapons transit route through Syria, and in the long term to ensure that the country will never become a platform to attack the Lebanese Shiite movement; to fight against a Saudi-led regional axis whose objective is to contain Iran’s rising geopolitical power; and to support a long-standing ally — some officials in Tehran speak of paying back an old debt owed to former Syrian President Hafez al-Assad for supporting Iran in its eight-year war with Iraq. In the event that Assad loses power, Iran fears that an implosion of the Syrian regime may enable the ascendance of an alliance of Sunni extremist groups that are anti-Shiite, anti-Iran, and anti-Hezbollah.

In the zero-sum competition between the Iran-led axis and Saudi-led coalition, it is hard to see how a nuclear deal will change the dynamics of the Syrian conflict. Although all regional actors pay lip service to the need for a political solution in Syria, none of them are yet willing to abandon their maximalist positions. In the absence of any diplomatic solution, Iran, Turkey, Qatar, and Saudi Arabia are all pursuing military strategies intended to tip the balance on the ground in favor of their respective proxies.