The Obama administration’s Syria policy has collapsed under the weight of a brutal assault on Aleppo by the forces of President Bashar al-Assad and Russia. Shrugging off global condemnation, Russia and Mr. Assad have dispatched their aircraft to attack schools and hospitals, singling out civilian targets to make the city uninhabitable and force its remaining population to flee.

Secretary of State John Kerry and other world leaders are now calling for Russia and the Assad government to be investigated for war crimes. But for the past year, Mr. Kerry had held firm to the belief that only through cooperation with Russia could the United States pressure the Assad government, reduce violence in Syria and move the country toward a political transition. The United States is now struggling to respond to the reality that Russia has little interest in a political settlement.

With an election days away, the Obama administration is reluctant to do anything that might tie the next president’s hands. Mr. Obama himself remains as resistant as ever to increasing involvement in Syria’s war. But continuing his hands-off approach will have crippling effects on his successor’s ability to make diplomatic progress.

Two steps are needed to advance America’s Syria policy. The first is to move beyond a discussion limited to no-fly zones or increased support to the armed opposition; the second is a cleareyed, fact-based assessment of just how risky further American involvement might be. Both are possible between now and when the next president takes office.