We must halt the massacre in Aleppo. Whatever the cost, we must stop the massive, random, indiscriminate bombings — and, worst of all, the discriminate ones aimed chiefly at civilians, humanitarian convoys and hospitals — that the forces of Bashar Assad and Russia have resumed with a vengeance in and around what was once Syria's most populous city.

We must call a halt in the days (if not hours) ahead to the rain of steel, the cluster and phosphorus bombs, and the barrels of chlorine dropped from low-flying government helicopters on the last parts of Aleppo held by moderate rebels. The world, with the democracies out front, cannot fail to respond to the horrifying images, relayed by the few witnesses still there.

Those images are of children's shriveled, vitrified bodies; of the wounded whose limbs, for lack of drugs, have been amputated by desperate doctors who are soon massacred themselves; of women mown down by rocket fire, as in Sarajevo 24 years ago, while waiting in line to buy yogurt or bread; of volunteers struck down while digging through the rubble in search of survivors; of human beings drained of strength, surviving in filth and waste, saying goodbye to life.