The present study examined how the pre-war debate of the U.S. decision to invade Iraq (in March 2003) was discursively constructed in pro- and anti-war newspaper opinion/ editorial (op/ed) argumentation. Drawing on theoretical insights from critical discourse analysis and argumentation theory, we problematised the fallacious ‘justification discourse’ used in the pro-war op/eds to build up a ‘moral/legal case’ for war on Iraq based on adversarial (rather than dialogical) argumentation. The proponents of war deployed ‘instrumental rationality’ (ends-justify-means reasoning), ‘ethical necessity’ (Bush’s ‘Preemption Doctrine’) and ‘humanitarian virtue’ (the bombing of Iraq to ‘save’ Iraqis from Saddam’s tyranny) to justify the pending invasion of Iraq. Their arguments intertextually resonated with Bush administration’s ‘war on terror’ rhetoric in a way that created a form of indexical association through ‘recontextualisation’. The type of arguments marshalled by the pro-war op/ed commentators uncritically bolstered the set of U.S. official ‘truth claims’ and ‘presuppositions’. The questions about the motives and legality of the war were suspended. Conversely, anti-war op/ed debaters dismissed Bush administration’s ‘neo-imperialistic’ reasoning and called into question the logic of militarist ‘humanitarianism’ by arguing that brute force and daylight ‘plunder,’ dressed up in moral grab and in the language of a ‘noble ideal,’ were part of a long Western colonialist tradition that glorified the allegedly virtuous role of the West as the ‘civiliser’ of distant cultural Others.