Story highlights Pentagon spokesman: U.S. believes it can work through issues with Afghanistan

Obama has grown increasingly frustrated in dealing with Afghan President Hamid Karzai

Until now, officials had been discussing plans to keep a small force in the country

If the U.S. pulls out all troops, it'll be a situation similar to that in Iraq

President Barack Obama is seriously considering withdrawing all U.S. troops from Afghanistan in 2014, a senior administration official told CNN.

The official's comments came after The New York Times reported the administration was looking at speeding up the troop withdrawal to the "zero option," leaving no U.S. troops in Afghanistan.

Until now, U.S. and Afghan officials had been discussing plans to keep a small force behind to fight insurgents and to train Afghan security personnel.

But Obama has, in recent months, grown increasingly frustrated in dealing with Afghan President Hamid Karzai.

Their relationship soured further last month after the United States and the Taliban planned peace talks . In response, Karzai cut off negotiations with the United States on the residual troop presence post-2014.

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A "zero option" has always been among the scenarios the United States envisioned. But the new revelation means that it could be a very possible one now.

Pentagon spokesman George Little said Tuesday that Obama has not made a decision on U.S. troop levels in Afghanistan beyond 2014.

"We are continuing discussions" with Afghanistan about carrying out post-combat missions, Little said. "We continue to work through issues," he said, adding, "We believe we can work through them."

If the United States pulls out all its troops, it will be a situation similar to that in Iraq.

The refusal by the Iraqi government to extend legal protections for U.S. troops after the end of the war in Iraq was a major reason the United States left the country with no residual military training force.

Karzai has said he would like for U.S. troops to remain after the end of the NATO mission. But he also has been highly critical of the troops over the years, following incidents in which U.S. forces have killed civilians.