Regardless of the “official Church position”, I’m sure thousands of Catholic wives, mamas and girlfriends all across the USA, many of whom had already lost one or more loved ones in WWII, were relieved that their men would be returning home and not have to fight a land war in Japan.
My husband, who enjoys online genealogy as his hobby, happened to find my grandfather’s WWII draft card online the other week. Granddad had to register for the draft in the fourth round. He was 61 at the time. They were registering men up to age 65. That’s how bad it had got.
Also, my dad was fighting in the Pacific at that time, so if the war hadn’t been brough to a swift end, I probably wouldn’t be sitting here to type this as I might not have ever been born. My uncle, Dad’s older brother, had already been killed in the Pacific at Midway, leaving no progeny.
Putting this in the past, I agree we should all work very hard for peace and to prevent ever having to use nuclear weapons in any conflict going forward.