The options, requested by the administration, include a range of troop numbers from zero to 10,000 US troops and reflect the long-running debate over how many are needed to train and advise the Afghan security forces and conduct counter-terrorism missions.
The official was not authorized to talk on the record by name and spoke on condition of anonymity.
Some US officials, including senior military leaders, have argued that the larger number is needed to conduct the multi-faceted mission and provide enough security for the troops and other Americans there.
Combat operations end on December 31. Earlier plans called for US and NATO nations to leave 8,000 to 12,000 troops in Afghanistan to advise and assist Afghan forces and do counterterror operations as long as Afghan leaders sign a security agreement.
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The decision on troop numbers has been stalled by Afghan President Hamid Karzai's refusal to sign the security agreement, which would provide the legal protections needed to enable US troops to remain in the country. The US currently has about 33,000 troops in Afghanistan.
Karzai was constitutionally barred from running for a third term.