I find it very difficult to articulate what I feel about this.
I have the utmost respect and gratitude for people who put their lives at risk to serve in the Armed Forces. I am well aware that the vast majority are highly motivated, patriotic decent people with a good set of values in place. I think the recent case is a tragedy all round.
BUT-
I agree that putting armed personel in a position where they are trained to kill, are under constant threat, have more likely than not witnessed carnage and atrocity at first hand, may have lost friends they were close to, is very likely to desensitise some of them. Not all, but some and probably more than we think. I don't particularly think these 3 young men were twisted; labelling them as such allows us to make their deed a further step beyond what 'we' could ever see ourselves doing. IMO put in just the right/wrong kind of circumstances many, man people are capable of terrible errors of judgement, getting carried away by the situation and ARE capable of awful actions that they will live to regret.
I don't 'know' the OP btw and do not wish to be bashing anybody. I have issues with the whole concept of sending people in to faraway sandy places for poorly justified reasons, and then being appalled when they find themselves in situations they are not equipped to cope with.