Oct. 24, 2008 -- Few issues so clearly divide Barack Obama and John McCain as the war in Iraq. Their differences were stark even before the war began: Obama opposed it, McCain favored it.
Then there was the troop surge: Nobody pushed harder for sending additional troops than McCain. Obama didn't just oppose the surge, he proposed the opposite, calling for the withdrawal of troops.
But in a September 2008 interview with Bill O'Reilly, Obama acknowledged that the surge had worked.
"I think that the surge has succeeded in ways that nobody anticipated," Obama said. "I've already said it's succeeded beyond our wildest dreams."
Another difference lies in the candidates' vision for the war. McCain says he'll withdraw troops, but only if security continues to improve.
"If you set a date for withdrawal, regardless of conditions on the ground, then chaos, genocide results," McCain said.
For much of the campaign, the war in Iraq has been a signature issue for Obama, having opposed the war since the beginning. Obama has supported a strict timetable for withdrawing combat troops -- all out within 16 months.
But there has been some evolution in Obama's position. He recently said that he reserves the right to "pause" the withdrawal if conditions deteriorate, and he speaks with less certainty about his timetable than at the beginning of his campaign.
"We should end this war responsibly. We should do it in phases," Obama said in the first presidential debate at the University of Mississippi. "But in 16 months we should be able to reduce our combat troops ... provide some relief to military families and our troops and bolster our efforts in Afghanistan so that we can capture and kill bin Laden and crush al Qaeda."
Obama's discussion of Iraq only includes combat troops, not complete withdrawal. He says that he'd still keep troops in Iraq for training and counterterrorism operations.
"When you add up the troops that will be required to do that, you end up with probably 30,000 to 50,000 troops by 2010 and perhaps 20,000 to 30,000 troops by 2012," said John Nagl, a retired officer in the United States Army and counterinsurgency expert.
As for the nation's other war, in Afghanistan, McCain favors sending more troops, following the military surge model used in Iraq.
"If I'm elected president, I will turn around the war in Afghanistan, just as we have turned around the war in Iraq, with a comprehensive strategy for victory," McCain said at a town hall meeting in Albuquerque, N.M.
But the implementation of the surge's lessons in Afghanistan could conflict with McCain's position on Iraq.
Top military commanders say that troops aren't available for deployment in Afghanistan until they are withdrawn from Iraq, putting McCain in a tight position.
"The improving situation on the ground in Iraq and the worsening situation on the ground in Afghanistan mean that whoever the next president is, he's going to have to pull troops out of Iraq to redeploy them to a front that we're not winning right now," said Nagl. "And the increasing demand of American forces in Afghanistan, it's going to be hard to balance those two demands."
Obama also favors more troops for Afghanistan, adding two brigades drawn from troops currently slated for Iraq. He also promises an increase in nonmilitary aid to the Afghan government of $3 billion to build infrastructure and restore community.
While the war in Iraq and Afghanistan has been overshadowed by the financial crisis, the cost of the two wars continues to mount in dollars and in lives, likely to resurface as a critical issues for the next president.