U.S. President Donald Trump said Wednesday he wants to return home all U.S. forces from Afghanistan before the end of the year, a deadline much sooner than one put forward by his administration earlier in the day.

“We should have the small remaining number of our BRAVE Men and Women serving in Afghanistan home by Christmas!,” Trump tweeted late Wednesday night.

The nation’s longest war began in 2001 when U.S. forces invaded Afghanistan, in response to the September 11 attacks on New York City and Washington, D.C.

The invasion toppled Afghanistan’s then-ruling hardline Taliban, which harbored the al-Qaida terror network and its leader, Osama bin Laden, the mastermind of the September 11 attacks. But the Taliban has waged a relentless and bloody insurgency against the U.S.-backed civilian government since its overthrow.

The U.S. and Taliban reached an agreement in February for the U.S. to remove all of its forces from Afghanistan by mid-2021 in return for assurances by the Taliban not to allow terrorist groups to use Afghan soil for international attacks.

The Taliban been engaging in intra-Afghan negotiations to reach an agreement on a permanent cease-fire and power-sharing arrangement in post-war Afghanistan.

Just hours before Trump’s tweet, National Security Adviser Robert O’Brien said the United States intends to reduce its troop levels in Afghanistan from 5,000 to 2,500 by early 2021.