President Biden will withdraw all U.S. troops from Afghanistan by Sept. 11, effectively winding down the conflict 20 years after it began, officials said. He is expected to formally announce the decision Wednesday, officials said, revising a Trump administration plan for a withdrawal by May 1.

The new deadline would coincide with the 20th anniversary of the terror attacks on the World Trade Center and the Pentagon in the US in 2001.

Biden has been hinting for weeks that he was going to let the deadline lapse, and as the days went by it became clear that an orderly withdrawal of the remaining 2,500 troops would be difficult and was unlikely. U.S. officials provided details on Biden’s decision on condition of anonymity, speaking ahead of the announcement. It was first reported by The Washington Post.

US and Nato officials have said the Taliban, a hardline Islamist movement, have so far failed to live up to commitments to reduce violence. And this decision will reignite political division over America’s involvement in what many have called 'the endless war'.

The move comes hours after it was confirmed that the Taliban and the Afghan government would take part in a US-led peace conference in Turkey, starting later this month.

The government of Turkey announced on Tuesday it will host a 10-day peace conference between Afghanistan’s warring sides from April 24. That surprise announcement came after a Taliban spokesman the previous day said his group would not attend a peace conference that had been tentatively planned to take place in Turkey later this week. 

US Secretary of State Anthony Blinken and US Defence Secretary Lloyd Austin are expected to brief Nato allies on the decision in the Belgian capital, Brussels, on Wednesday.

The United States has spent trillions of dollars and lost more than 2,000 service members since 2001 in what has been its longest war.