That "execution" photograph has been widely misunderstood. Taken out of context, it appears to be an inhuman act: I've read recently that the victim had been captured a few moments before, after he brutally murdered eight people, and the General "lost it" after viewing the bodies.
Not a vindication, by any means, but a "softening" of the cruelty. Still terrible, but more understandable.
The media seized that image, and published it with the full intent of having it stir up sentiment ... already highly opposed to a unjustifiable - and unpopular war... a distortion of the true situation ... with the idea that "the ends justify the means".