U.S. service members secure the perimeter at an undisclosed location in Afghanistan in March 2020. The U.S. has roughly 1,000 more troops in Afghanistan than it has publicly disclosed, The New York Times reported. The Pentagon maintains that 2,500 troops remain in the country. (Joel Pfiester/U.S. Air Force)

U.S. service members secure the perimeter at an undisclosed location in Afghanistan in March 2020. The U.S. has roughly 1,000 more troops in Afghanistan than it has publicly disclosed, The New York Times reported. The Pentagon maintains that 2,500 troops remain in the country. (Joel Pfiester/U.S. Air Force)

A Special Forces soldier secures the perimeter at an undisclosed location in Afghanistan in February 2020. (Joel Pfiester/U.S. Air Force)

This story has been updated.

KABUL, Afghanistan — The United States has about 1,000 more troops serving in Afghanistan than it has publicly acknowledged, a New York Times report said.

The number of American service members in the country was officially reduced to 2,500 in the final days of the Trump administration — the lowest level since the start of the war — but the number actually dropped to around 3,500, the newspaper reported Sunday.

The difference is the result of some special operations forces being “off the books” and some temporary and transitioning units being in theater, the report said. It cited unnamed American, European and Afghan officials.

The military’s method of reporting its overseas force numbers has drawn criticism before, including from then-Defense Secretary Jim Mattis in 2017, who pledged more straightforward accounting, shortly before the Trump administration began redacting numbers of troops in Iraq, Syria and Afghanistan from quarterly reports.

The latest discrepancy comes as President Biden weighs whether to pull all remaining U.S. forces out in the next 45 days under the terms of a U.S.-Taliban deal signed last February.

Some of the uncounted troops include Army Rangers, who work simultaneously under the Pentagon and the CIA while in Afghanistan, the report said. Washington has historically assigned service members to the CIA and other agencies and classified information about their presence.

Since 2017, the Pentagon has said that it does not include some transferring troops in its total forces reporting because the period between two units transitioning is usually very short.

The U.S. military in Afghanistan refused to answer questions about troop numbers when asked by Stars and Stripes and directed all queries to the Pentagon.

A Pentagon official told The New York Times that the number of U.S. troops in Afghanistan stands at 2,500.

The U.S. had previously undercounted its military presence in the country after an Obama administration drawdown supposedly brought the U.S. troop strength to 8,400. After Mattis expressed frustration with the way the numbers were counted, the Pentagon announced in late 2017 there were actually more than 11,000 troops there.

Under the deal last February, the U.S. agreed to a withdrawal of all foreign forces by May 1 if the Taliban meet counterterrorism pledges that critics have said are vague or unverifiable. The group insists it is meeting its commitments, which include not attacking foreign forces. The Taliban have threatened to resume attacks on foreign troops if they remain in the country past the deadline.

The Biden administration is in the process of reviewing the deal and whether to complete the pullout by May.

Former President Donald Trump campaigned on ending America’s longest war, now in its 20th year. But critics worried that his official troop drawdown from around 13,000 to 2,500 by January was based on political motives, and they said a full withdrawal in the coming months could benefit extremist groups.

In addition to American troops, there are roughly 7,000 NATO and coalition troops in Afghanistan training local forces.