The word kill in the sixth commandment in Exodus 20:13 can more accurately be translated as “murder.” In fact, most modern Bible translations, like the New King James Version, translate Exodus 20:13 as, “You shall not murder.”
Murder is defined in Noah Webster’s 1828 dictionary as, “To kill a human being with premeditated malice.” Exodus 20:13 reflects God’s value of human life and expresses that it should not be taken simply because of a man’s greed or hatred. This commandment is not directly speaking of accidental death or killing in wartime battles. In fact, Romans 13:1, 4, says that military personnel are God’s ministers executing His judgment on those who do evil:
“Everyone must submit to governing authorities. For all authority comes from God, and those in positions of authority have been placed there by God… The authorities are God’s servants, sent for your good. But if you are doing wrong, of course you should be afraid, for they have the power to punish you. They are God’s servants, sent for the very purpose of punishing those who do what is wrong.”
Source: https://www.kcm.org/read/question-of-the-day/do-soldiers-war-break-sixth-commandment-do-not-kill