The U.S. has reduced the number of U.S troops in Afghanistan to 2,500, the Pentagon announced Friday.

President Donald Trump had promised in October to bring all remaining U.S. forces in Afghanistan back home by Christmas. “We should have the small remaining number of our BRAVE Men and Women serving in Afghanistan home by Christmas!” he tweeted.

Hours before Trump’s announcement, national security adviser Robert O’Brien said the U.S. would reduce the current 4,500 troops in Afghanistan to 2,500 by early next year. It’s not the full withdrawal that Trump promised, but it is the lowest level of American forces in Afghanistan since 2001.

“Today, the United States is closer than ever to ending nearly two decades of war and welcoming in an Afghan-owned, Afghan-led peace process to achieve a political settlement and a permanent and comprehensive ceasefire,” the acting secretary of defense, Christopher Miller, said in a written statements. “Moving forward, while the Department continues with planning capable of further reducing U.S. troop levels to zero by May of 2021, any such future drawdowns remain conditions-based.”

A new law requires the Pentagon to send Congress an assessment of the risks before further troop withdrawals. That was not done in this case, Reuters reported, because Trump signed a waiver allowing the troop reduction after the move had already been completed, according to an Army spokesperson.

“Convention dictates that reducing troop levels, associated equipment and adjusting associated force protection requirements across a country-wide combat zone is not something that can be paused overnight without increasing risk to the force and core mission goals,” Army Major Rob Lodewick said Friday.

“I will always be committed to stopping the endless wars,” Trump said in a brief statement. The U.S. war in Afghanistan is America’s longest, having dragged on since 2001 at a cost of $2 trillion. At its height, the U.S. had over 100,000 troops stationed there.

President-elect Joe Biden will face a number of challenges when he takes office Wednesday. He has advocated for a light footprint in Afghanistan, but it remains to be seen whether he will listen to the generals or proceed with further troop cuts.