For the sake of discussing the principle of responsibility. Every person is responsible for their own actions, and we all reap what we sow, however, the level of blame depends upon the level of knowledge, and the maliciousness of the intent. Responsibility goes deeper than just actions, the weight of responsibility relies upon the motive and objective of the heart.
"...Whoso kills his neighbor ignorantly, whom he hated not in time past; As when a man goes into the wood with his neighbor to hew wood, and his hand fetches a stroke with the axe to cut down the tree, and the head slips from the helve, and lights upon his neighbor, that he die; he shall flee unto one of those cities, and live: Lest the avenger of the blood pursue the slayer, while his heart is hot, and overtake him, because the way is long, and slay him; whereas he was not worthy of death, inasmuch as he hated him not in time past." (Deuteronomy 19:4-6)
It is not wrong for sovereign lands to defend themselves, nor take offensive action to thwart an attack, nor take action against evil corrupt sovereignties, so when an enlisted solder is under the authority of government, they have the responsibility to take action under command with the knowledge they have in a responsible manner. This doesn't mean corrupt and hypocritical governments should be allowed to commit murder and oppression. All injustice needs to be punished wherever it is found, beginning with those in authority, but every man is responsible to act according to his conscience with the knowledge that he has.
People now a days have much more knowledge of what is really going on behind the closed doors of the governments of the world, because of the public information available, but back in the days of WW1, WW2, Vietnam, etc they had very little knowledge of what was really going on. The newspapers, the radio, and the television were the only mediums of information they had about government actions, and therefore their consciences were pure and blameless for the actions they took in line of duty.
When we all stand before God those soldiers under command will not be held accountable for obeying authority, unless they took malicious actions themselves against humanity. The manipulators and liars behind the scenes are the real murderers of mankind, even if they used innocent soldiers to carry out their evil agenda.
I agree with you in your verse citation. However, countries are not things that act, have rights, or bear responsibilities. Only individuals have those traits, and collectivism is neither rational nor scriptural.
Pleasure to discourse with you!