Citing U.S. Central Command, a Defense Department statement on Tuesday called the withdrawal "somewhere between 16% and 25% complete," adding that C-17 cargo planes have removed "160 loads of materiel and equipment" from Afghanistan so far.
A Central Command statement last week referred to the withdrawal as 13% to 20% complete.
Although President Joe Biden announced the Sept. 11 deadline for removal of all U.S. and NATO troops, in opposition to some Pentagon officials who prefer maintaining a residual ground force in Afghanistan, military officials are working with a mindset of a mid-July deadline, The New York Times reported on Wednesday.
After U.S. troops levels declined to about 3,500, down from around 100,000 in 2011, the amount of U.S. property to remove from Afghanistan is less than expected.
Kandahar Airfield closed in May, as did several smaller air bases, and fighter planes are departing Bagram Air Base, the largest U.S. base in the country, in favor of cargo planes.
Of particular interest is post-withdrawal security at Kabul Airport, the capital's civilian airport, and the possibility of an international presence to protect it.
"The Secretary [of Defense, Lloyd Austin] recognizes the key hub that is the airport there in Kabul and the impact that will have not just the United States but other nations in terms of their decisions about their own diplomatic presence," Defense Department spokesman John Kirby said on Tuesday.
"The president has been clear that we will maintain a diplomatic presence in Afghanistan going forward, and again, as I said, that means having that airport be accessible and open. And we're just not there yet in terms of what that looks like going forward," Kirby said.