[kahljorn]

"damage, being human lives lost. How many is acceptable?"

I don't know, but I think most people don't want to kill that many people and the international concensus (and I assume the international pressure) seems to be that nuclear war is a last resort and nobody really wants it even as a last resort because of the undesirable ramifications. In regular wars people die and what-not but it's not on such a mass indiscriminate way and moreover it doesn't ruin the entire land, rendering it useless for all parties.