On the "choice" issue, I think a lot of young people join the army without an adequate understanding of what they're getting into, or they were subject to high pressure salesman tactics of less than scrupulous recruiters. I am of the assumption that the vast majority of new recruits are very young. So while we have a "volunteer force" I do believe that the armed forces are "sold" to people as something they are not. Television and movie portrayals of war contribute to this, the military is not the only one complicit in glorifying what it is that they do.
Not to take away from the positives of the armed forces, I have many family members serving or who have served. But I won't fault a soldier who is serving in Iraq, for example, for their simple presence there on the basis that they chose to join the army/navy/air force. (@Shane, I don't think that was your point, but you made me think of this.) I will fault them for doing something wrong, to an extent, but of course then you also have to take into account all the psychological trauma and other issues swirling around serving in a war and what that does to your mind, as well as the military's responsibility to put people in the field who are capable of doing their job competently. E.g., not putting people who are apt to crack and do something horrible out in a war zone, or properly monitoring mental health and warning signs.