A negotiated outcome becomes possible only by changing the balance of power: a limited U.S. strike that sets back Assad’s military, followed by the training and arming of those vetted elements of the opposition that support a democratic, inclusive Syria and oppose al-Qaeda and other extremists.
Congress should adopt legislation that authorizes and urges the Obama administration to pursue such a policy.
The goal is fracturing the Syrian regime so political and military elements of the regime can join with moderate and democratic elements of the opposition to establish an interim government that can begin to wind down the war, protect all Syrians (including Alawites and other minorities) and go after al-Qaeda.
Such an outcome will be hard to achieve, and it will take time. The alternatives — an Assad military victory, a takeover by al-Qaeda and other extremists, a prolonged stalemate or descent into chaos — all threaten U.S. interests.
Having asked Congress for authorization, it will be virtually impossible for President Obama to take military action if Congress votes no. To mitigate the adverse consequences of a “no” vote, the administration would have to take bold action. Most are steps the administration should take anyway, but after a rebuke from Congress, they would be even more important.
In Syria, this means expanding and accelerating the training and arming of moderate, democratic elements and the provision of humanitarian assistance, especially to areas liberated from the regime. In Afghanistan, this means leaving a significant U.S. military force after 2014 to help stabilize the country and check Iranian activity. In Iraq, this means shoring up U.S. support for the government as it battles a resurgent al-Qaeda and seeks to resist Iranian pressure. In the region, this means strengthening diplomatic and security support to allies nervous about Iranian hegemony.
Otherwise, lack of U.S. military action in Syria will be read as a victory by Iran — making a nuclear-armed Iran and Iranian hegemony more likely.