Nope.
My copy of the commandments just says not to murder. I don't have that definition in my edition. It also doesn't seem to say anything about bombing an enemy city. I do recall a certain army calling on the power of God to destroy the whole city of Jericho, though. So I guess I'm not too clear on what the Lord may or may not think about taking the war into Japan proper. Someday maybe I'll ask Him.
But until then I do know something with reasonable certainty:
Attacking Japan with atomic bombs ended the war and saved many more lives than it took. Not merely American lives but certainly even more Japanese lives. Orders of magnitude more. The atomic bomb didn't so much change who died in Hiroshima and Nagasaki, but really just when and how. Add then every other metropolis in Japan. The fighting would have been bloodier and more appalling than the world had seen ever before, or frankly, since.
Weren’t there innocent people in Jericho? (Joshua 2)
The Old Testament wars were quite bloody.