WASHINGTON - Thirty-eight years ago today, a soldier fresh from Vietnam riveted the nation by recounting the horrors of a far-away war, famously asking the Senate Foreign Relations Committee: "How do you ask a man to be the last man to die for a mistake?"

The speech by 27-year-old John Kerry launched his rise from antiwar protester to presidential nominee to chairman of that very same powerful committee.

Tomorrow Senator Kerry will listen as veterans of the war in Afghanistan shine a spotlight on a conflict that a small but growing number of Americans are beginning to question, even as President Obama increases troops. But in a sign of how much Kerry - and the country - has changed since 1971, tomorrow's hearings will feature few - if any - dramatic calls for withdrawal.

Kerry's committee did not invite any witness from the Iraq Veterans Against the War, the modern-day analog of the antiwar group he represented when he testified in 1971. That group, which includes Afghanistan war veterans, has called for an end to the Afghan war. At least three out of the four Afghan war veterans who will testify tomorrow oppose a US withdrawal.

Kerry himself, now an elder statesman and key ally of the president, has resisted drawing parallels with Vietnam.

"In Vietnam, there was no threat to the United States in any direct form whatsoever," Kerry said in a recent telephone interview. "The consequence of not being in Vietnam was in no way to increase the danger to America. The exact opposite is true in Afghanistan with Al Qaeda. The threat is very real."

Still, the witness list has frustrated those who believe Afghanistan is on its way to becoming the next Vietnam.

"I was a little disappointed that there wasn't any outreach made to hear from veterans who are against the war in Afghanistan, given that he played a similar role in Vietnam," said Perry O'Brien, a medic who served in both Afghanistan and Iraq, and belongs to Iraq Veterans Against the War.

Back in the '60s, veterans who opposed the Vietnam war tried for more than four years to testify about their experiences, but the Senate Foreign Relations Committee called "everybody except soldiers," recalled Jan Barry, founder of the Vietnam Veterans Against the War.

In January 1971, the group conducted their own hearings, interviewing over 100 soldiers about alleged crimes against Vietnamese civilians and other dark aspects of the war. But the hearings, known as the Winter Soldier investigation, got little media coverage. So Kerry, an articulate Yale graduate who had recently returned from combat, suggested the group take its message to Washington. Weeks later, they camped on the national mall and began contacting members of Congress.

It worked. The State Department invited Kerry and Barry to brief officials and, at the last minute, the Foreign Relations Committee asked Kerry, whom Barry considered the veterans' most articulate spokesman, to testify.

Kerry stayed up all night writing what would become the most famous speech of his life.

"It was a moment to crystallize a lot of thoughts," Kerry recalled. "I was shocked to walk in there and see that I was going to be only witness."

Before television cameras, Kerry accused senior US officials of forcing soldiers to continue an unwinnable war. He said it was the height of "criminal hypocrisy" to say that America's freedom was threatened by what happened in the rice paddies of Vietnam. He recounted testimony from the Winter Soldier investigation, saying that crimes such as rape, beheadings, and random shootings at civilians occurred "on a day-to-day basis with the full awareness of officers at all levels of command."

The televised hearings changed the way many Americans saw the war.

"My grandfather, after seeing John Kerry on television, said he finally understood what I was talking about," Barry said.

The speech launched Kerry's career, but also may have planted the seeds of political defeat.

His antiwar stance made him an enemy of President Richard M. Nixon, who undermined Kerry by boosting another Vietnam veteran who accused Kerry of embellishing his war record. That man, John O'Neill, later appeared in the so-called "Swift Boat" ads that helped bring down Kerry's 2004 presidential campaign.

The ads stirred the anger of some veterans who felt betrayed by Kerry's antiwar stance, but Kerry said he has never regretted giving the speech.

"A few phrases might have been more artfully expressed, and there were a few things I left unsaid," he said. "But for an all-night effort, and the passion of the moment, and the honesty of the moment, I'm proud of what I said. I think it had an impact and it helped to save lives and end the war."

Kerry did not become the president in 2004 or secretary of state in 2008, a post many believe that he wanted. But today, he finds himself at the helm of some of the president's greatest foreign policy challenges: marshalling support for a climate change treaty, a ban on nuclear testing, and more funding for Afghanistan.

"He is at a very special moment in his career of public service," said Representative William D. Delahunt, a Quincy Democrat. "If one could write the history of his career trajectory, it is as if he was destined to be where he is now."

But much has changed since Kerry delivered his call to conscience four decades ago.

Anger over the Iraq war has been muted by Obama's pledge to withdraw most combat troops by the middle of next year. Afghanistan remains an escalating conflict, but many still support it as a necessary response to the Sept. 11, 2001, terrorist attacks.

With military deaths in the thousands, rather than tens of thousands, the two wars have not generated the same public clamor that consumed the country in 1971.

Tomorrow, at least three of the four Afghan war veterans invited to testify will say that the United States should stay in Afghanistan, even though there is no guarantee of success.

Westley Moore, a former Army captain, will call not for withdrawal but for "a smart victory," he said. Genevieve Chase, a reservist, will call for longer stints for soldiers so they can learn the culture and language, while Chris McGurk, a retired US army staff sergeant, believes that humanitarian assistance must be greatly improved. A fourth Afghan war vet could not be reached for comment.

But Kerry did not invite O'Brien, who opposes both the Iraq and Afghanistan wars, even though Kerry invited O'Brien to stay at his Nantucket home in 2006 during a film festival featuring an antiwar documentary that O'Brien was in.

Last year, O'Brien organized his own Winter Soldier hearings featuring testimony from soldiers about how "extremely loose rules of engagement" and air strikes in Afghanistan kill civilians and alienate the population.

"I think we presented clear evidence that soldiers were being ordered to do terrible things," he said. "But there wasn't much of a response."

Members of the group testified before the Congressional Progressive Caucus, but have never been invited to an official hearing.

A spokesman for Kerry's office said he is "looking for perspectives from troops who have spent time on the ground, without regard to their opinions about the war overall."

In an interview, Kerry said it is important "to let democracy work, in terms of airing differences and options."

Kerry is calling one witness who will urge a dramatic policy shift: Andrew Bacevich, a Boston University professor and Vietnam veteran who lost a son in Iraq.

"The significance of young John Kerry's testimony at that time was that it seemed to capture something very essential about the Vietnam war," said Bacevich. "I do believe that today, there is a fairly urgent need to pose the same essential questions."