Here's 1-20:
The Bible tells of seven things that God hates and counts as an abomination. (Prov. 6:16-19) He hates, for one thing, "hands that shed innocent blood."
Another typical passage: Ex. 23:7, " Keep very far from a false matter and [be very careful] not to condemn to death the innocent and the righteous, for I will not justify and acquit the wicked."
The Bible clearly commands, “You shall not murder” (Exod. 20:13). As I already already mentioned, the Bible does not forbid all killing, such as in capital punishment by the government, or a just national defense. However, murder (the intentional or indiscriminate killing of an innocent person or persons)is forbidden. The Bible uses the phrase “innocent blood” about 20 times, and in every instance condemns shedding innocent blood.
I will spare you the other 18 or 19 quotes --- although you can find them easily in any online Bible concordance -- but here's a 20th century updating which touches even closer on the matter at hand:
Catechism of the Catholic Church, para. 2314 :
"Every act of war directed to the indiscriminate destruction of whole cities or vast areas with their inhabitants is a crime against God and man, which merits firm and unequivocal condemnation." [Cf. Vatican II, Gaudium et spes 80]
This does not especify anyone by name who is thereby "damned." But it does show the shedding of innocent blood to be a damnable offense.
'Every act of war directed to the indiscriminate destruction of whole cities or vast areas with their inhabitants is a crime against God and man, which merits firm and unequivocal condemnation." [Cf. Vatican II, Gaudium et spes 80]'
Fortunately, I don't find the Catholic Church to be a reliable reference in the case of war, based upon its history.
In the case of H/N, there was a warning, so a claim of innocence would be hard to justify. There also was the edict from God to the nation of Israel to kill the Canaanites. Presumably, He found the children and old folks of them to be worthy of death or as culpable as the rest of them. The same could be said of the culpability of the Japanese people that supported the Japanese war machine.
At any rate, your statements leave no room for forgiveness, so the assurity of hell rings hollow.