As long as Tehran continues to provide military and financial assistance to the Syrian regime and its regional allies, including the Lebanese militant group Hezbollah, Assad will likely have the wherewithal to hold on to power. Reaching out to Tehran and convincing Rouhani to invest in a future relationship with a new Syria is thus essential to negotiating an endgame.
Washington should be under no illusions about how difficult it will be to secure Iran's cooperation on the Syrian front. The Iranian regime is itself deeply divided, and hard-line elements -- in particular, the Revolutionary Guards -- are operating inside Syria in support of the Assad regime. This powerful faction of the Iranian regime will not easily abandon its Syrian client.
Moreover, Assad and Hezbollah are two of Tehran's main proxies in the region, enabling Iran to wield widespread influence in the Shiite arc running from Iraq to Syria and Lebanon. Iran's growing influence has deeply concerned U.S. partners in the region, including Israel, Jordan, and Saudi Arabia -- one of the main reasons that Washington will have a tough time convincing them that reaching out to Tehran is a necessary step toward ending the conflict.
Nonetheless, Rouhani appears determined to pursue a more moderate course on foreign policy. Tehran has signaled a new readiness to engage Washington on regional issues as well as on its nuclear program. Iran is no doubt determined to maintain its influence in Syria. But if Tehran can be persuaded that dumping Assad will best protect its decades of investment in Syria while advancing the prospects for rapprochement with Washington, it may well throw its weight behind a negotiated end to the war.
Tehran has good reasons to head in this direction. Whatever the outcome of Syria's civil war, it is hard to imagine that Assad will be able to stay in power over the long run. As a result, Tehran has a vested interest in laying the groundwork for a constructive relationship with whatever government comes next. So, too, would Rouhani earn a significant measure of goodwill in Washington if he helped broker a peaceful resolution to the Syrian conflict.
The current trajectory of Syria's conflict is leading to state collapse and growing anarchy -- a situation that ultimately compromises the interests of all countries in the region, including Iran. Syria will never return to its prewar status quo, and the choice ahead is clear: either an escalating conflict that threatens the wider region or an attempt at a diplomatic process that seeks a cease-fire and a lasting political settlement.
An opportunity to bring Iran to the negotiating table may be close at hand. U.N. Secretary-General Ban Ki-moon recently announced plans to convene a Syrian peace conference in Geneva in mid-November, and the United Nation's special envoy for the Syrian conflict, Lakhdar Brahimi, has backed Iran's participation.
Adding Syria to the agenda for negotiations between Tehran and Washington does risk bogging down their dialogue over nuclear issues, but it could also tip the balance in favor of a deal. Cooperation between Iran and the United States on Syria would help build the mutual confidence needed for a breakthrough on the nuclear front.
Syria's humanitarian crisis is only mounting -- as is the risk that the civil war will engulf neighboring states. Now that the diplomatic door is ajar with both Moscow and Tehran, Obama has every reason to try to walk through it.