But in the past few weeks, a grim assessment from the US commander on the ground and flawed Afghan elections have strengthened the voice of the naysayers who warn of a costly quagmire – giving Mr. Obama pause. Obama now finds himself in a quandary, mulling over the options – from the full-blown counterinsurgency fight his generals advocate to a scaled-back, targeted approach more acceptable to critics of the Afghan war.
Amid calls from Republican lawmakers and even senior military offices to decide soon, Obama huddled with his national security team last week to determine the best way ahead. The delay in deciding indicates that the opponents have his ear.
It's no longer in America's interest to expend the resources needed to create a stable Afghanistan, critics say. Al Qaeda has left the country for neighboring Pakistan, leaving the United States and its allies to fight dangerous but less significant groups like the Taliban, they argue. Couple that with the time, lives, and money it would take to stabilize a country that's still a fragile patchwork of tribes, they add.
And for them, a key question is: How can the US be sure it will succeed where everyone from Alexander the Great to the Soviets have failed?
It's not worth it, says Andrew Bacevich, a former Army officer who teaches history and international relations at Boston University and who is a longtime critic of US foreign policy, particularly in Iraq, where his son died in 2007. He says American thinking on Afghanistan is too facile, particularly the idea that mounting a full-scale counterinsurgency there – with an initial surge in the number of troops – will prevent another 9/11-style attack on the US.
"The notion that fixing Afghanistan will somehow drive a stake through the heart of jihadism is wrong," says Mr. Bacevich, noting that Islamic militants flourish in many regions outside Afghanistan. "If we give General McChrystal everything he wants, the jihadist threat will still exist," he says.
The current debate is broadly bookended by two options: "double down" and send tens of thousands more US troops to mount a proper counterinsurgency, committing American resources for at least a decade to essentially build a nation from scratch, or walk back to a more targeted counterterrorism strategy that would conduct intelligence-driven attacks against Al Qaeda with minimal American "footprint." A third option, thought to be the most risky, is a hybrid of the two.
The first option, the counterinsurgency or so-called COIN strategy, is backed by Gen. Stanley McChrystal, the top US commander in Afghanistan. His assessment suggests that as many as 40,000 more troops are required temporarily to defeat the insurgency, protect the Afghan population – a central premise of counterinsurgency – and create a viable ally out of Afghanistan.
Critics such as Bacevich lean toward the second, more targeted option. But other military experts worry that scaling back would be seen as a retreat, a sign of weakness that would invite Al Qaeda to return to Afghanistan and plot more attacks.
"You give Al Qaeda some breathing room, you can bet they'll come after us," says Anthony Zinni, a former head of US Central Command who criticized the Iraq war but supports McChrystal's counterinsurgency plan. He is pushing for greater NATO support as well as reconciliation with some of the Taliban and other local groups to make the strategy work.
Without more forces on the ground, the US can't gather the intelligence needed to strike high-level targets, Zinni says. More troops would bolster counterterrorism efforts in nearby Pakistan, and also help train Afghan forces so they could eventually take over security operations.
Opponents of the Afghan counterinsurgency have allies in high places – Vice President Joe Biden and possibly National Security Adviser James Jones, who signaled this summer that he didn't think more troops were the answer.
Their arguments were bolstered by allegations of fraud in the recent Afghan elections, which reinforce the view that Afghanistan's government is too weak a partner on which to build a counterinsurgency strategy. The elections cast serious doubt on the legitimacy of President Hamid Karzai and his government, raising questions in the Obama administration about the wisdom of allying with a government perceived as corrupt.
But past events also weigh heavily on the debate. The new must-read among Obama's top advisers is a 2008 book about Vietnam called "Lessons in Disaster: McGeorge Bundy and the Path to War in Vietnam." As national security adviser to presidents Kennedy and Johnson, the late Mr. Bundy supported deepening US involvement in Vietnam but had second thoughts later in life.
Afghanistan and Vietnam are similar, says Gordon Goldstein, the book's author and a former adviser to the United Nations. Mr. Goldstein points out that President Kennedy went against military advice when he moved to reduce American involvement in Vietnam before he was assassinated. His instincts were right, Goldstein says, though it remains unclear what impact Kennedy's reluctance to send troops into Vietnam would have had on the broader conflict.
"I don't think the strategy [of more troops] was a viable strategy in Vietnam and I don't think the strategy is viable in Afghanistan," he says. Former US commander of Afghanistan Dan McNeill has said that going by counterinsurgency doctrine, Afghanistan would need a force of at least 400,000 to win. There are currently 100,000-odd foreign troops in Afghanistan, not counting local indigenous forces.
Afghanistan's historic resistance to outsiders worries him, too. Both the British and the Soviets failed to hold the country, with the Soviets leaving in 1989 after 10 years fighting local insurgents. "Afghanistan is a small power that is extraordinarily resistant to great powers, the great power," says Goldstein.
Still, McChrystal's recommendations have strong backing from the top brass, including Gen. David Petraeus, commander of US Central Command, and Adm. Mike Mullen, chairman of the Joint Chiefs of Staff.
That makes it harder for Obama to reject McChrystal's proposal. Doing so could alienate the military, says Robert Scales, a retired Army two-star general and military historian.
Mr. Scales says he thinks Obama will ultimately shoot down the middle and go for the hybrid option – what he calls "McChrystal Lite." That means sending in some more troops, but fewer than what McChrystal wants, and targeting key members of terrorist networks.
Retired general Zinni agrees. "They are in danger of buying into a counterinsurgency strategy and doing it on the cheap," he says.