Moses completes his narrative of the progress of the Israelites from Egypt and talks about the conquests that lie before them.
They destroy people as vehicles of God’s judgement. When they do this they are not needlessly malicious. They are being like earthquakes, or hurricanes, or old age or sickness. God is the creator, that status means that in bringing physical death he is not a murderer. Most armies pray to God for victory, but this is unique. He is using this nation as part of his plan, he is having them bring judgment on the people along the path.