The essential principle is immutable: we should never go to war unless we have been attacked or are under direct, immediate threat of attack. Never. And never again.Exactly.
Personally, I based my opposition to the Iraq War on the United Nations. If a country cannot convince the United Nations Security Council to approve an aggressive war -- or cannot convince even a significant minority of the Council that a war is justified -- then its wrong to go to war, it isn't justified.
What we already know about what happened in Iraq during this war is sickening --from White Phosphorus in Fallujah to vicious ethnic cleansing in Baghdad. Once the US soldiers are gone, the stories yet to be told will be truly horrifying.