When the Bush Administration's case for war in Iraq shifted from the existence of weapons of mass destruction to the existence of "weapons of mass destruction-related activities", director Robert Greenwald got angry. Uncovered: The War On Iraq is his response; a powerful, well-constructed and sober documentary that - via a dense collection of interviews with intelligence experts, diplomats, weapons inspectors, and politicians - painstakingly and ruthlessly takes apart the American government's changing arguments for invasion.

In 2003, Greenwald read about the Veteran Intelligent Professionals for Sanity, a non-partisan group of former CIA employees, whose clear-headed, rational critiques of the claims being made in favour of war were making persuasive reading in left-leaning US political journals like Counterpunch. Starting with the VIPS' Ray McGovern, Greenwald went on to interview concerned operatives, image analysts, strategists, and experts from the highest ranks of the CIA and diplomatic service. The results were published as a 56-minute DVD, and distributed through grass-roots democracy organisations.

"AS AN ARGUMENT, UNCOVERED IS A TRIUMPH"

Greenwald expanded his film to feature length after establishment pillar Dr David Kay of the CIA's Iraq Survey Group made his famous statement to the US Senate in January 2004: "We were almost all wrong." The interview with Kay dominates the final 20 minutes, and alongside the testimony of weapons inspectors Hans Blix and Scott Ritter, provides a conclusion chilling in its obvious lack of political bias.

This is not a crowd-pleaser in the vein of Michael Moore's Fahrenheit 9/11 - in some respects it is barely a movie at all - but witty juxtaposition of footage does eke out the odd disbelieving laugh amongst the seriousness, rarely more so than when McGovern destroys, with unarguable authority, Colin Powell's much publicised presentation to the UN point-by-intercut-point. As an argument, Uncovered is a triumph; as a historical document, it is of profound importance.