The military is only pissed because this photo somehow leaked out to the media somehow and they have to angerly defend it when in truth and reality, there are much much worse things that US soldiers and Marines do outside of the rules of war to the enemy and innocent civilians conducted on a daily basis than urinating on dead bodies.
Murders, rapes, torture, body part amputations, beatings, abuse etc and many of the victims are not enemies trying to kill while in direct conflict but innocent civilians at the hands of American soldiers.
The military knows it and decides to either do something or nothing at all strictly handled in-house and military politics plays a huge role in their decisions.
The military with the media's help, continues to try and depict the US military and it's personnal as outstanding in every way with a few isolated incidents involving wayward soldiers (and that small segment of soldiers is huge) when that's total b.s. and no matter how much you train military personnel to follow the rules of wartime and everyday military standards, many solders and marines will do these things and much worse and it not only because of any substandard training that's documented and can be revealed, but just like in everyday American society, that's just their individual/collective inherent nature(s) and much of that comes from home; their rearing, upbringing, beliefs, way of thinking and if you joined the military to become a "hardcore gung ho John Wayne" type with no remorse of feelings or compassion, then this stuff happens all the time on a regular basis.