It's interesting the amount of shock this has generated. We have a lot of people upset about the inhumane death of an innocent puppy and calling for the head of this marine. Some are able to pick up on the mental illness (but he should still be killed painfully, that shameless fuck, right?).
Do you know what it's like to be exposed to what they are over there? This marine, somebody's beloved son and family member, may have had to deal with unimaginable, tortuous, psychological damage that you could never begin to comprehend. War is a very, very ugly thing. Sometimes, when people, especially very young people, are exposed to these terrors they develop psychological barriers that help them cope. Actions are not always reflecting the inner feelings. Remember when you were in 6th grade and may have laughed while describing something horrible...because you were nervous and embarassed, not because you advocated the horrible event you described.
This marine situation should be looked at with less off the cuff reaction and more analysis and understanding. It's not as simple as you want to make it. Not only is war very ugly, but also very complex, and it does horrible things to people. This young marine is reacting to his environment...an environment where HUMANS die everyday at the hand of other humans. An environment where survival really could depend on getting rid of a dog. So let's say this marine is tasked with the job. He is young, immature, nervous, and vastly, irreparably, psychologically damaged by last week's experiences. He is in a fog and has completely lost touch with himself. He grabs the puppy and on some level (a level which he has been forced to abandon in order to ensure his survival)realizes the horror of the situation he is in. Like the giggly sixth grader, he makes a joke and tosses it over the edge. Can you see the psychology here? Of course everyone on this thread will come back and say no, he's just an asshole. But really, consider the circumstances, the pressure, the horror. Do you think that killing a puppy was the worst thing he encountered that day? He is in a different world and doesnt' make decisions like he's living in a posh apartment in London or New York.
I'm not argueing the validity of this war...I'm just saying that it is his reality, and if you haven't been through it, perhaps you're not equipped to walk in his shoes and know what was going on in his head.