The battlefield around Aleppo is a mess — a crosshatch of different combatants and foreign forces. Within a small area are Syrian regime forces backed by Russia and Iran; Kurdish rebel forces backed by the United States; Turkish forces that are shelling the U.S.-backed Kurds; Arab rebel fighters supported by the CIA and Saudi intelligence; Jabhat al-Nusra fighters allied with al-Qaeda; and Islamic State fighters, who want to kill all of the above.

A full cease-fire in this landscape is impossible right now — and not just because Kerry has been too trusting of the Russians. The combatants have to sort themselves out. Rebels will vote with their feet whether to ally with Jabhat al-Nusra and the Islamic State. Saudi Arabia and other Arab patrons will have to lean hard on “moderate” rebels to pull them toward the cease-fire group and away from the terrorists.

If the Russians keep bombing the rebels around Aleppo willy-nilly, that will sabotage any hope of a truce. Here again, blame Moscow if it blocks de-escalation.

Going forward, the United States needs more military leverage to match Russia.