The international community does have one more option for intervention in Syria: concerted Western/Russian efforts to an immediate cessation of hostilities and of arms shipments from all quarters, including Russia, to both sides in the conflict. This would be followed by negotiations, without preconditions, for a post-war Syria.
This idea was first advanced by Moscow over a year ago, and was basically agreed upon by US Secretary of State John Kerry and Russian Foreign Minister Sergei Lavrov at their meeting in June. The stumbling block has been the refusal of some rebel representatives to participate. The West should use its powers of persuasion on the responsible opposition, thus marginalizing the extremists whose influence in a future Syria is rightly feared. Otherwise, this path to a peaceful outcome will remain on the table obscured by the current dangerous drumbeat to war.
David C. Speedie is director of the US Global Engagement program at the Carnegie Council for Ethics in International Affairs.