Doesn't that mean all wars are immoral (irrespective of the justifications like defense)? Would you say that the military too should not be allowed to ever kill anyone? If no, I see an inconsistency that needs to be explained.

If someone will not submit to the judgement of the law then it's permissible and indeed often necessary to kill them. But if someone gives themselves up or is captured then they should not be killed. In the same way soldiers in a war have a right to surrender, and those who surrender should not be killed - but it's permissible to kill those who don't.

This seems like sound reasoning. Thanks for wording it so clearly.

No inconsistency whatsoever - the discussion is about executions as a penalty in a judicial context.

Police, militaries and individuals should all have the right to employ potentially deadly force if required and justified within a legal context.

Yes, that makes sense. I like lmm's comment below that clarifies why these contexts are different.

If there is no way to save a life (or several) other than to use lethal force against the attacker, then I wouldn't consider it murder, but (self-)defense. Otherwise, I couldn't care less if it's legal or who does it, it's not justified.

Aren't they? Shouldn't there always be at least one side in the war that isn't just trying to protect their own life?

Killing someone in self-defense (if your own life is in danger and there is no other way out) is quite universally accepted I would think.

Of course this will get quite interesting very fast if an invading army just walks around not trying to shoot anyone.

The challenge here is to help create a world where militaries who kill people are no longer necessary.