"Stuff happens!" Donald Rumsfeld once exclaimed in response to a reporter's question about the looting of Baghdad after the U.S. invasion of Iraq in 2003. "Freedom's untidy," he went on to explain, "and free people are free to make mistakes and commit crimes and do bad things. They're also free to love their lives and do wonderful things, and that's what's going to happen here."

Now David Hare, Britain's foremost political playwright, has borrowed Rumsfeld's phrase as the title for an ambitious new drama that drills deep into the motives, morality and mental gyrations behind the decision to go to war in Iraq. Hare is a certified leftie of the European variety -- in newspaper articles he has thundered piously over the purported illegality of the Iraq campaign -- but his play, staged at the National Theatre here, is a nuanced tragicomedy that allows members of the Bush administration to make their case even as it piteously dissects their arguments. It's the intellectual's "Fahrenheit 9/11."

Hare has stitched together a sparse but gripping narrative from various factual accounts, relying especially on Bob Woodward's "Bush at War" and speeches and public statements for shards of realistic dialogue. "Nothing in the narrative is knowingly untrue," he writes in an author's note. "Scenes of direct address quote people verbatim. When the doors close on the world's leaders and on their entourages, then I have used my imagination. This is surely a play, not a documentary."

Hare doesn't spare the rod or the satire as he lines up the Bush administration's cast of usual suspects. A hyper-charged, grinning Rumsfeld and a dark, abrasive Dick Cheney come in for their share of abuse. "I never met a weapons system I didn't vote for," quips the vice president early in the proceedings, only he's not kidding. There's a buffoonish George Tenet, displaying aerial spy photos of an alleged Iraqi weapons manufacturing plant yet refusing to make a firm identification. And a coy, slippery and manipulative Condoleezza Rice, who is constantly interpreting her boss's thoughts and is said to keep two mirrors in her office "so she can see her back as well as her front."

The tragic hero in Hare's rendering is Colin Powell, who watches with growing anxiety and anger as Cheney, Rumsfeld & Co. blithely navigate the ship of state toward war. While Paul Wolfowitz is telling Bush that invading Iraq and overthrowing Saddam Hussein "is something we can do with very little effort," Powell pleads patience, demanding that the administration at least go through the motions of seeking international consensus and support at the United Nations. The Middle East, he warns, "is a tinderbox. And the current level of thinking from some people in the administration seems to be, 'Okay, so let's throw in a match and see what happens.' " Yet Powell also has a soldier's sense of loyalty to his commander.

The other character pleading caution is British Prime Minister Tony Blair, but Hare cannot resist painting him as a preening, self-centered and self-righteous figure who says he wants to "reorder the world" for moral purposes but who is more interested in sticking close to the heart of power in Washington than to his principles. "With the Americans there's one rule," he tells his aides. "You get in early. . . . You prove your loyalty. And that way they listen." Only in the end, they don't.

But the most intriguing and enigmatic figure is the man at the heart of the drama: President Bush. Early on, Bush comes across as an amiable but simpleminded zealot, somewhat amazed that he has ascended to high office. "I am here because of the power of prayer" is his explanation. Bush jealously guards both his prerogatives and his words, as if using too many might somehow weaken him. "That's the interesting thing about being the president," he tells Blair. "I don't feel like I owe anybody an explanation."

Hare has written in the Guardian of his belief that "the overriding offense of all of us in Europe, on whatever side of the argument, has been to have peddled the notion that because Bush is inarticulate, he must therefore be stupid." And Bush as portrayed in "Stuff Happens" is no Bible-spouting buffoon. He quietly orders Rumsfeld to draw up a secret plan for invading Iraq while he goes about the charade of seeking international support. "They say I'm a mad Texan, bent on war," he tells U.N. chief weapons inspector Hans Blix. "That's not so."

Hare's Bush shrewdly knows where to draw the line. And he's the only character who in the end gets exactly what he wants. He senses that Blair will loyally back him, and therefore he is willing to allow Blair and Powell to seek a second U.N. resolution authorizing war, over the heated objections of Cheney and Rumsfeld, because he understands that Blair needs the effort as political cover back home. He tolerates Powell's internal dissent and personal discomfort until he decides the time has come to draw the line. Then he puts it squarely to Powell: "I've taken a decision. . . . It would be a big thing if you disagreed. Well?"

And Powell submits: "I don't disagree."

After Powell leaves, Bush looks up at the audience: "I didn't need his permission," he says.

Because Hare is a playwright first and a polemicist only after that, he understands it is more valid artistically to give the Devil his due, and "Stuff Happens" contains passages that passionately lay out the case for war. He knows that most people in the audience inevitably will be antiwar but, unlike Michael Moore, he seeks to challenge their comfortable assumptions. An anonymous journalist asks how we would respond if a dictator in Europe had slaughtered half a million people, as Hussein did in Iraq. "Would we ask, faced with the bodies . . . faced with the ditches and the murders, would we really stop to say, 'Can we do this?' "

Likewise, a politician concedes that America and Britain went to war on false premises and then botched the postwar occupation. "Practices evolved on the ground which everyone admits were unworthy of a great cause," she acknowledges. "But the action itself remains pure."

Still, for Hare, this is not enough. By his own accounting, the decision to justify the war on the dubious grounds that Hussein possessed weapons of mass destruction was a cynical and duplicitous one, based on flimsy intelligence that Washington and London hyped to support a preordained conclusion. He abhors the casual bullying of allies and U.N. weapons inspectors, and points to the stark reality that terrorism has increased as a result of the Iraq campaign.

Hare is especially hard on Americans, complaining that "the infantile psycho-babble of popular culture is grafted opportunistically onto America's politics." He has no patience with the notion that the Sept. 11, 2001, attacks had such profoundly traumatic impact that those who aren't Americans couldn't possibly understand. "On September 11, America changed," complains one anonymous Briton. "Yes. It got much stupider."

Some critics have complained that "Stuff Happens" ultimately engages the intellect but not the emotions. Hare refuses to make the easy case against the war, piling on the moral complexity to the point where many may leave the theater both deeply angry and equally ambivalent. Such may be the nature of the entire Iraq affair. Hare gives the last word to an unnamed Iraqi exile. "They came to save us," he says of Bush and Blair, "but they had no plans."

Alex Jennings as President Bush in "Stuff Happens," a compelling look at the decision to go to war in Iraq. David Hare rooted the play in various factual accounts, including Bob Woodward's "Bush at War."