[e12e]

If you're inclined to go down that path: the Japanese treated US POWs terribly, and the US still dropped two nukes as a weapons test (there was credible intelligence Japan was in the process of surrendering because of the "regular" fire-bombing campaigns - but dropping nukes was seen as a great deterrent against Sovjet. And as a great opportunity for a field test).

Note: I'm mentioning this because you're scenario isn't quite as hypothetical as one might hope - for neither those bombed nor for the abused POWs.