It’s probably the most important decision of his young presidency.

The fate of American troops – and the lives of Afghani men, women and children – rest on the outcome of Barack Obama’s speech this week authorizing sending more troops to Afghanistan, and a planned pullout in 2011.

It’s not the first unenviable choice Obama has had to make, nor likely the last. The economy still haunts the American people. Health care reform remains on the legislative table, its outcome unknown. The president is heading to Copenhagen to grapple with the ongoing crisis of climate change in a political atmosphere in which the chances for radical solutions, at least from this country, are hampered by their potential short-term economic impact.

But before getting too caught up in the magnitude of difficulties Obama is facing, let’s remember that he ran for the job, and won. The American people – and the rest of the world – want change. And progress.

The question is whether escalating the Afghanistan effort, even with a more clearly defined mission and exit strategy than in the past, is the right move.

DEMOCRATIC PRESIDENTS SEEM TO BE CURSED WITH THE NEED TO APPEAR TOUGH.

It’s to Obama’s credit that he’s taken some time to reach the decision, and to the deep discredit of critics like Dick Cheney, who got us into this mess, that he’s been accused of “dithering.” But it remains to be seen whether the new strategy – it’s too soon to call it a policy – will work.

Sorting out the competing views of administration officials, generals, the Naval Postgraduate School military experts quoted in this week’s cover story, veterans who’ve done time in Afghanistan and those who think we should simply get out is pretty close to impossible. History may be written by the victors, but in this case we need a better understanding of what “victory” might entail. Overpowering the dwindling Al Qaeda forces in the mountains between Afghanistan and Pakistan? Forging a better life for the Afghan people? Pressuring the Karzai government to embrace more democratic practices, even as his brother is accused of ties to the opium trade?

The comparisons to the American adventure in Vietnam, where we propped up a series of corrupt leaders before leaving the field of battle and returned to our own divided nation, are frightening, as they should be. Even if the Taliban represents a foe far worse than Ho Chi Minh and the National Liberation Front, the outcome ofthis renewed struggle is in serious doubt.

One trusts that Obama is making his decision based on what he sees as the facts, and not on campaign positions that are meaningless compared to the suffering that will be inflicted if we fail – or, for that matter, even if we succeed.

The fact that George W. Bush should have pursued Osama bin Laden when he had a chance doesn’t require us to continue to be there, further risking blood and treasure. While Obama is clearly a more honorable man than his predecessor, and at minimum will not involve us in a walk-up to war based on trumped-up charges of weapons of mass destruction, the jury is out on whether his decisions will work.

In modern history, Democratic presidents seem to be cursed with the need to appear tough, even when they doubt the recommendations of their generals, as JFK did regarding the military advice he was getting on Vietnam. A completely anti-interventionist stance is consistent with a deeply honorable pacifist strain in American history. But it also delayed us from coming to the aid of Bosnia and, to the Clinton administration’s deep regret, from trying to prevent genocide in Rwanda.

The American peace movement appears caught off guard – too invested in Obama’s election, and his personal popularity and intelligence, to mount the kind of concerted anti-war rallies that took place against Bush and Lyndon Johnson.

And the media are more involved, as usual, in other issues of the day – like what Tiger Woods was doing on Thanksgiving weekend, and how the reality show couple crashed the state dinner – to give this issue the attention it so badly deserves. What’s an independent-minded dove to do?

Speaking personally, as someone who was in the streets trying to stop the Vietnam War, I had nodoubts, then or now, that our involvement was ill-advised. I also had little doubt that those who were romanticizing the NLF, bombing buildings and hurting innocents to “bring the war home’’ were involved in an extremely dubious, dangerous game. Playing the Afghan card, similarly, is not something to be undertaken lightly. We’ve looked for the light at the end of the tunnel before, and just seen darkness.

One hopes that this time, “finishing the job’’ means something other than staying the course.