killing foreign soldiers is absolutely murder

Not especially. But okay.

they were plenty barbaric

No they weren't. In war, you either have to be the noble white knights in shining armor or the scariest dragon. We certainly weren't the knights in shining armor, and we sucked at actually being scary. We should have had mass reprisals against civilians as SOP. Instead, we just killed them accidentally - pissing them off just as much without getting any benefit from it.

the only place where US is good at war is in hollywood movies.

Tell that to the Japs.