No dollar amount has been decided. Estimates range from $1 billion to $10 billion a year -- and that includes military expenses, hardware and training, the whole deal that Afghanistan couldn't afford on its own.

"These are really funny numbers because no one knows the extent of what the U.S. is willing to offer," Lemmon notes.

Whatever amount Obama administration floats will have to win approval from Congress.

Former U.S. Ambassador to Afghanistan Ronald Neumann told CNN Friday that he thinks the total bill is going to depend on military presence. At a minimum, he figures, the United States will spend $5 billion in aid and military, not counting what would be spent for embassy costs.

Those numbers cannot be calculated in a vacuum either. As a discussion at the Brookings Institute involving the former U.S. ambassador to Afghanistan noted, Afghanistan is facing a major economic downturn after 2014.

A lot of money that has gone into Afghanistan has been wasted, numerous reports have shown. In 2011, one non-partisan group told Congress that the United States was wasting $12 million a day among contracts issued to support American efforts in Iraq and Afghanistan, CNN reported.

Even Karzai, prompted by a question from a reporter, said Friday "We have corruption."

Who is the U.S. talking with and why?

Last May, Obama made a surprise visit to Afghanistan, where he gave a speech about the end of the war.

He said, "We're pursuing a negotiated peace" with the Taliban.

To be clear, al Qaeda and the Taliban are two different entities, though there are ties. Al Qaeda is a terrorist group created by Osama bin Laden. The Taliban has provided shelter and support to al Qaeda.

In its newest incarnation, the Taliban has new, and some younger-generation, members who say they want to find peace with the United States.

In short, this is a complicated topic, as Foreign Policy detailed in December.

Former Ambassador Neumann said it's wrong to call it a negotiation.

Instead, he said, it's "a group of multiple players we are only talking to. We are trying to see if there's negotiating room."

On the Afghan side, a November poll by the independent San Francisco-based group Asia Foundation found that more than half of Afghans felt that their country was moving in the right direction. That includes agreeing with the negotiation of government officials and those trying to work toward peace to talk with and find common ground with militants.

Will the U.S. public stay interested?

There were complaints during the U.S. presidential election that Obama and Republican challenger Mitt Romney did not talk enough about Afghanistan.

But polls have shown that most Americans are tired of the war. A CNN/ORC International poll in September showed that only 3% named Afghanistan as one of the most important issues facing the United States. Earlier in 2012, CNN polling indicated that only 25% of Americans favored the war, and 55% said the United States should remove all of its troops before 2014.

Defense Secretary Leon Panetta pushed back against that figure at the time, saying polls don't fight wars.