The Canadian Broadcasting Corporation used to have a show called Talking To Americans, where a mischievious Canadian reporter, Rick Mercer, would interview Americans in the street, academics and politicans and get them to agree to absurd things like Canada should adopt the 24 hour day, or the U.S. should "bomb Saskatchewan" (a prairie province in Canada, although he made out it was a rogue state). It was funny, but a tad disconcerting, how gullible Americans can be.

There's something of that in watching Why We Fight, although it's no joking matter. The BBC Storyville documentary is a level-headed account of how the US public have been duped by their government and, fired by blind patriotism, marched into a war that never ends. "Our cause is just and we will defeat the enemies of freedom," says Bush. But people interviewed in the street, a new conscript, arms factory workers, and even those who support the war don't seem to know what that cause is.

We're in similar territory to Fahrenheit 9/11, The World According to Bush (Le Monde Selon Bush), and other documentaries questioning the "War on Terror", but Why We Fight places the US hostilities toward Iraq within the historical context of international aggression by what Gore Vidal dubs the "United states of Amnesia".

It's not just that Bush and his cronies had an agenda for invading Iraq prior to 9/11. That's now widely known. Rather, the doc argues persuasively, the U.S.A. is a nation pre-programmed to wage war. The economy and corporate America needs war to make money. Congress needs the defence contracts for the jobs back home. Politicans need to look strong to get re-elected. The military needs to justify its place as the most powerful force in the world.

The film uses as a starting point President Eisenhower's famous "military-industrial complex" speech to the nation in 1961. "Only an alert and knowledgeable citizenry can compel the proper meshing of the huge industrial and military machinery of defense with our peaceful methods and goals," he says.

However, the country is now invested to the hilt in its military and the citizenry are dozing. It just takes a president willing to pull the trigger, which is every president since the Second World War, and BOOM...

Director Eugene Jarecki, who previously made the incisive The Trials of Henry Kissinger, covers a lot of ground in the short space of the film. Visits to arms shows, military bases and archival newsreel spanning over half a century illustrate how entrenched militarism has become. Stealth fighter pilots who dropped the first bombs in Gulf War II talk like boys with toys about the excitement of being able to try out an enhanced guided bomb in a real life situation. Experts, retired US-military officers, and politicians shred homespun myths about fighting to "spread democracy and freedom."

Although Jarecki clearly takes a side, he doesn't hit you over the head with a sledgehammer. The spectrum of voices is a credit to his journalistic rigour. One moment, it's Rumsfeld in familiar, unctious guise courting the White House press. The next, interviews with Iraqi people, including some particularly gruesome pictures of air strike victims, remind us that the U.S. is far from winning the peace and how far the country has moved from 9/11 where as, one commentator says, "We had the world behind us."

At times, the documentary skates too quickly across a point. For instance, presidential advisor Richard Perle says in defence of the criticism that the White House has been hijacked by a cabal of extremists that, "We are not the same people that we were before." Is this an admission of mistakes and that experience has changed them? Who are they now, then? I wanted to hear more about why think tanks are so bad. The doc moves along too fast to make it clear.

If the doc at times feels scattered that's probably because it is difficult to attack a system rather than a person. It's not surprising that individual stories stand out. As well as the drama of political intrigue and Bushite corruption, the story of a retired NYPD Seargent and Vietnam vet who lost his son in the 9/11 attacks is particularly poignant. He describes with disarming candour how he wanted to see bombs drop and bodies pile up to avenge his son's death. That the Bush regime suggested Iraq was the guilty party was enough for him to get behind the war. Later in the film he describes his anger at having been lied to. "They exploited my patriotism," he says.

The main problem with the film is that it's coming out too late (2006 release in the States). It should have come out before the presidential election. Still, the point made about the Bush administration's enthusiasm for pre-emptive strikes is topical given recent reports that the Pentagon has lowered its threshold for making a nuclear attack.