Aleppo is the critical pivot of the Syrian civil war. Assad, backed by Russia and Iran, simply cannot abandon the city to the US / UK / Saudi / Turkish supported rebels without losing the war. The US and its allies know that if they lose Aleppo, the rebellion will be to all purposes finished from that point, though the killing and destruction and bloodshed will no doubt continue for some time. So each side is pouring in hardware, munitions, air power, special forces and everything they've got into taking a city still inhabited by over a million people.
And of course civilians - men, women and children - are caught up in the conflict and are killed on both sides, every day. A new and rather revolting twist to the agitprop war being fought in Europe's media is the publication by both sides of the child casualties of Western weapons. A small boy blasted to pieces by a Russian-made rocket; a small girl eviscerated by a British-made mortar round. All that's lacking is the juxtapositioning next the horrid corpses of the fat cat arms dealers, politicians and primitive Saudis grown sleek as butter from the war's profits.
Neither side holds the moral high ground. Neither side in battle ever does. Both sides have abandoned the peace table to see who can win Aleppo first; for after the slaughter, the side eventually planting its flag on the high pile of Aleppo's corpses will have the negotiating advantage.
But please, for as long as our purblind politicians back the killers of one side over the killers of the other, let's please refrain from moral pontificating. We're all just as guilty of those child deaths as eachother.