God knocked down the walls of Jericho, but afterwards the Israelites went in and put the city to the sword, apparently with God's blessing:
Joshua 6:20
20 So the people shouted when the priests blew with the trumpets: and it came to pass, when the people heard the sound of the trumpet, and the people shouted with a great shout, that the wall fell down flat, so that the people went up into the city, every man straight before him, and they took the city.
21 And they utterly destroyed all that was in the city, both man and woman, young and old, and ox, and sheep, and ass, with the edge of the sword.
None was spared except for Rahab and her family.
And in Deuteronomy 20:16:
16 But of the cities of these people, which the LORD thy God doth give thee for an inheritance, thou shalt save alive nothing that breatheth:
17 But thou shalt utterly destroy them; namely, the Hittites, and the Amorites, the Canaanites, and the Perizzites, the Hivites, and the Jebusites; as the LORD thy God hath commanded thee:
Judging from the history in the Bible, there are times when God condones the destruction of cities and sometimes commands it. I'm not implying that the United States was acting on specifically on God's orders, but instead was doing everything that it could to end the war quickly and victoriously. Oceans of blood have been spilled in humanity's wars throughout history. The enduring lesson of war is that only decisive victory brings lasting peace. The United States is arguably the most humane nation that has ever existed on the planet by virtue of its enormous power of destruction and its sparing use of that power. That is perhaps what irks its detractors, that something so powerful must be at its heart, evil, and yet it is not.
The mouth of the Lord can order such things, just as He could order the slaying of Isaac. Woe to the mere man who thinks he can do so, for such is delusion. I give you post #40, above.