A Pentagon spokesperson said Wednesday that 11,000 U.S. troops are currently in Afghanistan, thousands more than the previously acknowledged 8,400.

The 8,400 number did not include troops on temporary assignment, according to the Pentagon. Acknowledging the higher number is a matter of "transparency," which Defense Secretary Jim Mattis is demanding as the U.S. prepares to deploy more forces to Afghanistan.

Pentagon press secretary Dana White said in a briefing, "The secretary has determined we must simplify our accounting methodology and improve the public's understanding of America's military commitment in Afghanistan."

NPR Pentagon correspondent Tom Bowman reports that the practice of not including troops on temporary assignment in the official tally began in the Obama administration, which had set an upper limit of U.S. troops in Afghanistan at 8,400.

A defense official told Bowman that the accounting method allowed for more flexibility in meeting temporary needs.

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