I joined the anti-Vietnam War movement as an 18-year-old college student, a freshman at Columbia University. It was the fall of 1965, just months after the U.S. began sending ground combat troops to Southeast Asia.

The older members of the Columbia chapter of Students for a Democratic Society explained to me that unlike World War II, Vietnam was an imperial war, a war of occupation whose purpose was the repression of a national liberation movement. We were a small group then, but over the next three years SDS became a critical part of a larger antiwar coalition. Our anger mounted, our protests grew and our ranks burgeoned. Unfortunately, we went many bridges too far and got ensnared in the hallucination of revolution. By 1969, it became more important in SDS to fight each other over who had the "correct revolutionary line" than to fight against the war itself.

Early the next year, while the war was still raging, my own faction, the Weathermen, made the stupid and ultimately disastrous decision to disband SDS and opt instead for "armed struggle," our middle-class version of urban guerrilla warfare. Predictably, we became isolated and irrelevant over the ensuing years, even as the larger antiwar movement went on to achieve its goal: U.S. withdrawal from Vietnam.

I often wonder what would have resulted over the long haul if SDS — which represented the radical, anti-imperialist wing of the antiwar movement — had not chosen to self-destruct in violence and fantasy but instead had kept plugging away, encouraging more and more people to understand and oppose the building of an American empire.

This question seems particularly relevant today, 40 years later, as a reawakening antiwar movement prepares to confront many of the same issues. Who benefits and who loses from an American empire? What are the moral and economic and spiritual costs to Americans? Is a system of international law possible as an alternative to endless use of American military power? Viewed against the bleak future that Bush, Cheney, Rumsfeld and Rice are offering Americans and the rest of the world, these questions begin to seem more practical than idealistic.

What's hard to understand — given the revelations about the rush to war, the use of torture and the loss of more than 2,000 soldiers — is why the antiwar movement isn't further along than it is. Given that President Bush is now talking about Iraq as only one skirmish in an unlimited struggle against a global Islamic enemy, a struggle comparable to the titanic, 40-year Cold War against communism, shouldn't a massive critique of the global war on terrorism already be underway?

Yet the movement has remained small and politically isolated since the original outpouring of opposition in the spring of 2003, during the run-up to the war. In part, it was the victim of its own early success, the spontaneous demonstrations involving millions of people in the streets here and around the world trying to stop the war before it began. When this initial outburst failed, many became demoralized and hopeless.

Then, in 2004, most of the pent-up antiwar energy flowed into John Kerry's campaign, with little to show for it but further demoralization. The movement caught a second wind with the energizing presence of Cindy Sheehan, but it remains small compared with the outpouring against the Vietnam War.

Probably it's because there's no draft now. Clearly the fact that middle-class boys across the country were receiving draft cards and lottery numbers went a long way toward helping spur resistance to the Vietnam War. Nor is there a countercultural movement today that questions authority like the one that emerged in the 1960s and 1970s.

But building a movement can be done. To increase our ranks, we'll need to break through the too-common belief that change is impossible.

We'll also need to take on the larger war. As the next battle heats up, perhaps against Iran or Syria, the movement will have to ask the American people to look honestly at who we are in the world. The antiwar movement will have to engage in the most difficult dialogue of our lives with our neighbors.

Throughout American history, popular movements have made vast transformations in the social and political geography of this country — the abolition movement, the women's suffrage movement, the civil rights movement, the labor movement, the gay movement.

My own contribution is to tell the story of how an antiwar movement involving millions of people accomplished something unique in American history and almost unique in the history of empires: We helped stop a war of aggression by our own country. This was American democracy at its best. I lived through it, I saw it with my own eyes.

If all of us "gray-hairs" were to tell our stories, we might be able to make a contribution. At least we could help people find hope in this dark time.

Mark Rudd, who led the student uprising at Columbia University in 1968 and then became a member of the Weather Underground, teaches math at a community college in New Mexico.

© 2005 Los Angeles Times