Allen was tasked with developing an overarching plan for how U.S. forces will leave Afghanistan over the next two years, as well as solidifying a post-international combat troop presence. Now he has offered three distinctive options for the president, according to senior defense officials.

The officials said Allen's plans - created with input from Defense Secretary Leon Panetta's office, the Joint Staff, the U.S. Central Command, and the White House - would give President Barack Obama options based on what he is looking to do in Afghanistan.

The plans are awaiting official approval from Panetta, the officials said.

The low-end option calls for 6,000 to 6,500 troops that would be strictly for counterterrorism operations: hunting down Taliban and al Qaeda members and cells still operating around the country. This would require mostly Special Operations Forces, with a limited number of support troops and only a very small amount of training assistance for Afghan forces.

The mid-range option, involving around 10,000 troops, would still have the main focus on counterterrorism operations, but it would have a bigger training footprint for Afghan forces, with most of the focus on Special Operations troops and a limited amount of conventional troop training.

The 15,000-troop option would bring in a greater number of conventional troops for training Afghan Security Forces, as well as a bigger support element in addition to the counterterrorism forces.

Last spring, NATO and the Afghan government agreed on a plan for the United States and international forces to end the NATO mission in Afghanistan and hand over full security responsibility of the country to the Afghan government. At the end of last September - as the final troops added during the "surge" that Obama ordered in December 2009 left Afghanistan - the president ordered Allen to assess the situation in the country and develop an exit strategy.