The series of events leading up to the US invasion of Iraq on 19 March 2003 is examined from the perspective of theoretical and practical rationality and in the light of The National Security Strategy of the United States of America, the Charter of the United Nations (1945) and elements of just war theory. Strikingly, even without assuming the authority of the Charter of the United Nations and the validity of just war theory, the decision to wage war pre‐emptively and outside the bounds of international law proves to be equally unjustifiable on pragmatic grounds alone.