My take on the killing of civilians.
Have we killed civilians? Yes we have, and to great regret, but look at the numbers. We have killed probably several hundred civilians, but how many has Saddam killed? An even better question is how many more would he have killed had we left him alone? I think it's fair to say that Saddam would have killed far more people in the future than we have so far. People were going to die in Iraq regardless of whether we went in or not, but by going in we have assured the number will be the lesser and not the greater. This by itself makes it worth it.
Like Spock said, "the needs of the many outweigh the needs of the few."