Marine Corps Gen. James Mattis, outgoing Central Command chief, said he recommended to the Pentagon and White House that a postwar force of 13,600 U.S. soldiers, sailors, airmen and Marines remain in Afghanistan after the administration's 2014 withdrawal date.
Gen. John Allen, former head of all U.S. forces in Afghanistan, suggested as little as 6,000 U.S. soldiers or as many a 10,000 could remain in country after 2014.
Administration officials have also floated the notion of leaving no American soldiers behind after the withdrawal deadline.
That said, Mattis said Tuesday that his recommendations are only one several possible postwar force scenarios currently being debated inside the Pentagon and administration.
Army Gen. Lloyd Austin, who has been nominated to replace Mattis as the head of Central Command, will be the top U.S. officer in the region to oversee that postwar force once the troop numbers are finalized.
Mattis's comments come a day after NATO Secretary General Anders Fogh Rasmussen said the alliance plans to have its postwar strategy and troop numbers finalized by June.
"I would expect [troop numbers] to be finalized very soon because we also need to start planning," he said after Monday's meeting with Afghan president Hamid Karzai.
While the actual force numbers are still in flux, Rasmussen was was able to provide Karzai and other top Afghan defense officials details on the NATO postwar mission, dubbed Operation "Resolute Support."
"It takes some time to stand up a new training mission," he said regarding the NATO postwar mission. "Of course, and we will need the clarification [from Kabul] within the next few months" before the operation can begin in earnest.
During February's State of the Union address, President Obama announced the administration would be pulling out half of the 66,000 American service personnel in Afghanistan by this spring.
The final 32,000 American forces remaining in Afghanistan after this spring's planned troop withdrawal will start coming home following the country's presidential election in April 2014 — officially ending America's combat role there that same month, former Defense Secretary Leon Panetta said.