It seems reasonable to assume that many of those who are programmed to kill are capable of indiscriminate taking of others lives or their own.
PTSD has been promoted by the quadruple tours of duty that Bush advocated.
In a way, the Iraq and Afghanistan forays have done more damage to human beings than just killing innocent civilians. They have created military zombies as was the case during the Vietnam War to return home to dysfunctional lives without the support of the administrations that sent them there.
If you really want to support troops, tell them to object in the first place and for those there bring 'em home.