The report comes at a time when the Biden administration is reviewing last year’s peace with the Taliban on a full troop withdrawal from the country by May 1.
The New York Times reported late on Sunday the presence of some temporary and transitioning units accounted for the additional troops.
It said the troops included Joint Special Operations Command units, some of them elite Army Rangers working under the Pentagon and the CIA in Afghanistan.
Having more forces in a country than the officially acknowledged by the Defense Department was a common practice, the newspaper added.
“We are still at 2,500” in Afghanistan, Maj. Rob Lodewick, a Pentagon spokesman, said in an email to The New York Times.
About 2,500 American troops are still in Afghanistan, according to Pentagon officials, but The Times said the actual number was around 3,500.
Under their agreement with the Trump administration, the Taliban insist on a complete pullout of Americans from Afghanistan.