This discussion is also important for Afghan leadership to hear, says Larry Korb, a senior fellow at the Center for American Progress.
"They have to basically put Karzai in this place," he says. "He's been talking about 'You guys are causing me problems, we don't want you here.' "
Floating the Zero Option may be a way for the White House to gain concessions from Karzai.
"I think the president is saying, 'Look, if you don't go along with what I want—providing us with immunity and giving us control over operations—we're not going to stay there.'"
American troops withdrew from Iraq after President Nouri al-Maliki denied them immunity for combat operations, he adds.
"People thought, 'Gee, we would never do that.' I think Maliki himself probably thought that. It's important to keep in mind, it takes two to tango here," Korb says.
Omar Samad served as Afghanistan's ambassador to France and Canada in the last decade. He tells U.S. News he is surprised by the news in the last 48 hours, particularly given the U.S. and NATO's previous commitments.
"Not having that in place would not only jeopardize all the gains achieved over the last decade, but also would leave Afghanistan in a very precarious situation," says Samad, now an Afghanistan analyst with the U.S. Institute of Peace.
This instability could boil over into the region, he says, and may cause more global security issues.
He also points to the second critical role of the allied forces in Afghanistan: funding. Security forces in the volatile country are not yet mature enough, well trained or equipped to do the job themselves by 2014.
"It would be dramatic, and probably not very well received by the Afghan people in general," he says, adding, "that option can be viable only if we have a political settlement of the Afghan problem, meaning some kind of reconciliation with the Taliban that leads to a peaceful end."
This component, not training Afghans, is key to ending the war, says Korb.
"You don't have to train the Afghans to fight. They know how to fight," he says. "The real question is whether they'll fight for whatever the government may be."
The U.S. has already won the war, he says, pointing to the killing of Osama bin Laden.
Innocent adds the withdrawal will be left to how the White House handles its portrayal, and whether it can depict it as an "honorable exit."