Powers will tend to declare their means of war legitimate and the means of war available to their enemies to be illegitimate.

I think it's simplistic to declare our enemies "evil" because they're denied access (fortunately) to the kinds of expensive weapons systems that our own propaganda views with approval.

Are you seriously saying that going to a Labour party youth camp to kill teenagers one by one to "eliminate the next generation of leftist" is somehow not evil?

Or that strapping a bomb to a random kidnapped 9-year old girl is not evil?

It is Evil. Full stop. No discussion.

Whether someone else is also evil or not doesn't even come in to play.

Agreed.

Intentionally trying to blow up non-combatants is bad - and there is no way to make it good. Its one thing if non-combatants are collateral damage (war is dirty), its another thing entirely if ones intention is to intentionally kill civilians.

But what if intentionally blowing up a hundred civilians saves a thousand more? That's one argument used to justify the bombing of Hiroshima and Nagasaki for example, and the carpet-bombing of Germany. Many people have also disagreed with those arguments, but especially in the case of Germany it kind of was of a "kill some civilians to save many more" type of trolley problem – the greater Holocaust effort was stopped in more or less the earlier rather than later stages (I'm not very familiar with the Pacific war, so less comfterable commenting on that).

And what is a "civilian" anyway? Is someone who works in a gun factory a civilian or are they a legitimate target? What about a jeep factory? Or a factory which produces just some parts? What about the factory that provides steel? What about the lorry driver delivering the steel? Is someone who actively works to spread disinformation to justify something like the Russian invasion a civilian? Does it matter if they genuinely believe their own disinformation or if it's proven they know it's false?

In principle I agree with you as such and I think very few people disagree, but it's all pretty murky because most modern wars consist of much more than just soldiers going at each other. You need to look at the specifics of the situation in every single case.

I can defend Hiroshima and Nagasaki as military targets. I actually have a greater trouble defending the firebombing of Tokyo (though, its pretty clear to me that the capitol of a combatant country is probably a valid target for bombing in a declared war) because of the sheer number of casualties.

One of my gripes about WWII in the Pacific Theatre, is some folks get very bothered by use of nuclear weapons, while ignoring or downplaying the use of incendiaries, which often killed far more people.

In this case our enemies deliberately targeted civilians and then justified that choice by saying that since the US is a free country, by definition all of our citizens are just as guilty as our gov't and military are. I'm pretty comfortable calling that evil.