There are no easy solutions to the humanitarian crisis in Syria, least of all the Obama administration’s futile pursuit of a multilateral diplomatic initiative to end the war. The best-case scenario of such a settlement (assuming a highly unlikely change of heart by Russia and the acquiescence of Iran) would mean a Lebanon-style interim power-sharing formula, which might cut down on the violence but only at the cost of stunting Syria's political recovery. This is precisely why the rebels will never agree to it.

Absent a workable plan for saving lives or a compelling strategic rationale for intervention, the United States should stay out of the conflict—while using all means short of force to dissuade the participants and their regional backers from committing egregious human-rights abuses. Once the smoke clears, Syria will need a benefactor with clean hands to help it pick up the pieces.