Was the 2003 United States led war against Iraq justified? Many observers and ordinary citizens believe that to be an unjustified war, particularly when it came to light that there was little evidence that Iraq was in a serious position to build nuclear weapons. But many of these critics will have a more positive opinion of the 1990-1991 war, also waged against Iraq, which was carried out in response to Iraq’s unlawful invasion of Kuwait. And virtually all readers will agree that the war fought by the Allied Forces against Nazi Germany was a just war. What are the principles by which we can assess the justness or the unjustness of a given war? The identification of such principles is what a just war theory aims to do.