“I told him America can’t fight without planes, girlfriends, pizza and macaroni. But our jihadis can live on stale bread.” So says Abu Jandal, Osama bin Laden’s former bodyguard, who argues with a prospective jihadi that the murder of American innocents on 9/11 was justified, a simple strategic strike that represented a great symbolic victory. “Tarzan wanted to enter the region,” he says, meaning the Middle East. “Now he must pay the price.”

Jandal’s views are as chilling as they seem incredible, and one might reasonably wonder why he chooses to commit them to film. Now living in Yemen, ostensibly rehabilitated and having lost his taste for al-Qaeda’s doomsday tactics, he has granted interviews to The New York Times and 60 Minutes. And he is the subject of Oscar-nominated filmmaker Laura Poitras’ remarkable new documentary, The Oath, the second entry in her New American Century trilogy after 2006's My Country, My Country.

As a storyteller, Poitras is at once provocative and probing, and if her style draws us in with footage that could be described as misleading – Jandal is far more compassionate than he initially seems – she delivers a thoughtful portrait of a difficult subject. Jandal is, it turns out, not a violent revolutionary recruiting would-be suicide bombers. Who he is, and the lessons he imparts to his young Yemeni followers, are far more complicated, but always guided by a rigorous adherence to what he regards as Islamic principle.

Jandal is not the only subject of The Oath, but the other – Salim Hamdan, recruited by Jandal in his al-Qaeda days, imprisoned at Guantanamo Bay and accused of aiding terrorism – is seen only twice in a short, grainy interrogation video. His onetime mentor clearly feels responsible for his arrest: He avoids Hamdan’s wife and children if he can help it, and prays for Hamdan’s survival. Remorse over Hamdan’s fate appears to have had an impact on Jandal’s curiously ambivalent worldview. He still believes American leaders are guilty of aggression and genocide, but is no longer willing to do lead a scorched-earth crusade against them.

According to the Yemeni judge who oversaw Jandal’s rehabilitation after his 2000 arrest following the U.S.S. Cole bombing, the former bodyguard was once an extreme radical, dedicated to violence. But three years of re-education inspired a change: He became an exemplary student, all but renouncing his oath of fidelity to al-Qaeda, and after 9/11 provided U.S. authorities with a wealth of intelligence now considered indispensable to national security, weeping at the thought of old friends being coaxed by bin Laden into mass suicide.

That oath, in case you were wondering: “I pledge to God to assist and support, regardless of my own self-interest or reasoning, regardless of my own well-being; and not to challenge the leadership.” It seems almost something out of an Orwellian parody, like the mantra of the dedicated soldiers in Animal Farm: “I will work harder, Napoleon is always right.” But its implications are far more disquieting.

As Jandal observes, Osama bin Laden was working with true believers, not hired mercenaries, who would sacrifice themselves to humiliate America. And in responding to the 9/11 attacks by waging war in the Arab world, the U.S. is creating new jihadis all the time. Even Jandal’s young son, who once aspired to become a mechanic, now wants to join the cause.

Jandal, who drinks Coke and British ginger beer and allows his son to watch “Tom and Jerry” reruns, is not without his share of respect for his enemy, and still worries – apparently sincerely – that America will wipe out the Islamic world. “You are supporting Western-made goods?” one follower asks. “These Westerners are infidels, but they make things with sincerity and conscience,” Jandal replies with a laugh. “Our manufacturers are sons of dogs and cheaters.”

Yet perhaps the most telling moment in The Oath comes when he reveals, almost unwittingly, the seeming disconnect between his unyielding philosophy and his willingness to act. Asked if he would have participated in bin Laden’s attack on America, Jandal (whose official al-Qaeda title was “Emir of Hospitality”) says no, explaining that martyrdom is always an option, but that he prefers to be a soldier only on a true battlefield. (The next day he asks that the footage be deleted. No dice.)

Poitras constructs her fascinating, gracefully told story by mixing interviews with Jandal, scenes of him navigating the streets of Yemen in the cab he has driven since his release from prison, and updates on Hamdan’s high-profile trial, which concluded with his own release in January 2009.

They are all compelling: In Cuba, throughout much of the last decade, Hamdan rots away, separated from his family as he waits (and waits) for his day in court. In Yemen, Jandal suffers the uncertainty of a man who seems to acknowledge, however tacitly, that he has broken his oath, and that the penalty might mean death, torture and eternal damnation. He is powerfully conflicted and fiercely protective of his son, but driven by conscience.

And yet, despite whatever small hope of moderation is implied by Jandal’s story, there, in archival footage from a 1998 interview, is bin Laden himself, ominously predicting a black day for America, vowing to wipe the U.S. from the face of the earth. The message is no less disturbing today than it was then.