I would point to this Albert Einstein quote when asked why we went into Iraq:
The world is a dangerous place to live; not because of the people who are evil, but because of the people who don’t do anything about it.
I know it may not reflect a lot of the reasons we went to Iraq, but it can surely apply. Saddam was/is an evil man, and not one of his neighbors was willing/able to stop him. We did, and that’s not all bad. Sure, there is a tremendous cost involved both financially and in human life, but the truth of the matter is that there have been less people killed in Iraq since the invasion than Saddam killed in just 14 months of brutality (according to the prosecution).
I’m not trying to make a political statement – just trying to validate Einstein’s opinion in the quote above, since I do believe he was 100% right in his assessment about danger.