During the collapse of the old world the idea of nuking the Ultras was brought up fairly frequently. We will forever be grateful that cooler heads prevailed, and save for two instances the superweapons remained in their silos.
There were several reasons given for this restraint.
First off, at the start of the crisis, no one was quite willing to go that far. The folk of the old world simply couldn’t imagine their civilization ending. Even as Prevailer’s uprising spread the news media of the time covered it in terms of a ‘disturbance’, an ‘outbreak’, a ‘regrettable incident’, or even a terrorist attack. The West didn’t understand that it was being invaded and subjugated for what seems to the modern eye like an embarrassingly long time. They presumed that everything would get back to normal, that they’d rebuild the toppled cities and put the world to rights. Nuking their own nation would have required giving up these delusions.
Next, Ultras didn’t gather except in population centers. The First Defiance, and equivalent uprisings which created the pantheon, didn’t involve battle lines between human armies and Ultra gangs. They involved human armies being overrun and torn asunder by berserk demigods. The Ultras never really assembled in formation. The only times that they were gathered together and not in motion were when they occupied conquered cities. Destroying your own population to save it was harsh medicine, and few decision makers could bring themselves to do such a thing.
Most importantly, however, nuclear attacks only destroy most Ultras. The ones that are the biggest problem, those who pose the greatest threat, tend to have Ultra Toughness of at least level two. When Israel nuked the unoccupied section of Crete where the Great Summit was being held they successfully caught the Regime’s delegation with a powerful fusion bomb. Most of the Ultras were instantly obliterated. Prevailer, however, is Ultra Tough two, and survived with a minor battering. Mithras, of the Pantheon, was standing within several hundred feet of the bomb when it went off. His invulnerability was captured on camera, as he had been streaming the whole event for his young son to watch. Mithras had Ultra Toughness three, and didn’t even get knocked off his feet when the bomb detonated.
It is to the lasting credit of the old world’s leadership that we avoided nuclear winter. The temptation to strike out as their order was dismantled must have been overwhelming, but somehow they refrained. Nowadays it is likely that only the Union, and certain particularly organized sections of the Pantheon, retain the ability to launch nuclear strikes. This worldwide disarmament is one of the few positive consequences of the world’s current state. Nuclear Winter seems unlikely to be our fate.