During World War II, Academy Award-wining director Frank Capra cranked out a seven-part series titled Why We Fight. Given what had precipitated the U.S. entry into the war -- the bombing of Pearl Harbor -- the answer would seem rather obvious.

Not so for much-less-well-known award-winning documentary director Eugene Jarecki, who recently decided to ask the same question, though this time not to limit it to one war or one decade or even one century.

Instead, Jarecki took it upon himself to ask why we -- the U.S. -- seem to be frequently, if not constantly, at war with someone, from the Cold War to the war in Iraq. His conclusions seem disquieting, to say the least.

He begins with a farewell -- President Eisenhower's farewell, that is, the speech Ike made shortly before making way for JFK. It's a surprisingly good speech for a man remembered more for his deeds than his words. And in it he coined a phrase that would one day be at the center of much of the debate over how we defend ourselves: "the military-industrial complex."

Eventually, Jarecki links Ike's speech to that of another former general turned commander-in-chief, George Washington's farewell to Congress, in which he warned lawmakers of the dangers of standing armies and involvement in foreign intrigue. Intriguing, no?

But Why We Fight is more concerned with the present than the past, and it isn't long before Jarecki turns his camera to a long list of interviewees, including Sen. John McCain, former CIA operative Chalmers Johnson, noted neoconservative William Kristol, noted author Gore Vidal, White House adviser Richard Perle and Eisenhower's son, John, and granddaughter, Susan, who offer insights into Ike's battles with the Pentagon over its ever-escalating spending and his personal opposition to dropping the atomic bomb on Hiroshima.

But Jarecki is probably even more effective when he takes his camera off the big names and turns it on people like Wilton Sekzer, a retired New York City policeman who lost one of his two sons in the World Trade Center. Sekzer and Jarecki recreate Sekzer's ride to work on the subway that day and his reaction when he saw the twin towers burning.

More importantly, Jarecki documents the rest of the story: how an angry Sekzer, who once had served as a door gunner in a helicopter in Vietnam, cries out for revenge and eventually writes the U.S. military and asks them to put his son's name on a bomb headed for Baghdad -- and how an angry Sekzer got even angrier when he heard his president finally 'fess up that Iraq was not behind the destruction of the World Trade Center.

Jarecki is equally at home with Karen Kwiatkowski, a retired lieutenant colonel who served as an Africa/Middle East affairs specialist in the Pentagon and was alarmed when she heard White House advisers begin to beat the drums of war in Iraq. "Follow the money," she advises. And Jarecki does -- only to discover that the military-industrial complex has taken on a third partner, Congress, and a fourth, think tanks, such as the Project for a New American Century, which drew up the plan for regime change in Iraq years before President Bush took office.

Why We Fight has its flaws. Jarecki interviews so many people and weaves their stories in such an intricate pattern that it's often hard to remember who's who and who said what. For comment on the press, he turns to Dan Rather, who, for all his journalistic accomplishments, is probably not the most credible expert on the subject. And he clearly gives more screen time to liberals and discouraged conservatives than he does to practicing neo-cons, who, in the latest run-up to war, clearly had more to say about why we fight than anyone else.

And yet it's hard to fault a man who's willing to take his cameras not only to the streets of America, where he lets men, women and children have their say, but to the streets of Baghdad, where he finds voices that rarely if ever make it to American TV or movie screens. He even gets comments from an Iraqi doctor who helped treat civilians who awoke to find smart bombs tearing apart their houses one March morning.

It's hard work, and hard to watch at times. But it's oh so worth it.