President Barack Obama will keep 5,500 US troops in Afghanistan when he leaves office in 2017, according to senior administration officials, casting aside his promise to end the war on his watch.
Obama had originally planned to pull out all but a small, embassy-based US military presence by the end of next year, a timeline coinciding with the final weeks of his presidency.
But military leaders argued for months that the Afghans needed additional assistance and support from the US to beat back a resurgent Taliban and hold onto gains made over the last 14 years of American bloodshed and billions of dollars in aid.
The president was to announce the changes today from the White House. Officials said he would outline plans to maintain the current force of 9,800 troops in Afghanistan through most of next year, then draw down to 5,500 troops in 2017, at a pace still to be determined by commanders.
The officials previewed the decisions on the condition of anonymity because they were not authorised to discuss the matter publicly ahead of the president.
US officials have been hinting at the policy shift for weeks, noting that conditions on the ground in Afghanistan have changed since Obama's initial decision on a sharper troop withdrawal timeline was made more than two years ago.
The White House has also been buoyed by having a more reliable partner in Afghan President Ashraf Ghani, who succeeded the mercurial Hamid Karzai last year.
"The narrative that we're leaving Afghanistan is self-defeating," Defence Secretary Ash Carter said yesterday during a speech at the Association of the US Army. "We're not, we can't and to do so would not be to take advantage of the success we've had to date."
While officials said the Afghan policy had been under review for several months, Obama's decision to leave more forces in Afghanistan than initially envisioned was reinforced when Taliban fighters took control of the key northern city of Kunduz late last month, prompting a protracted battle with Afghan forces on the ground, supported by US airstrikes.
During the fighting, a US airstrike hit a hospital, killing 22 people, including 12 Doctors Without Borders staff and 10 patients.
Beyond the recent security troubles in Afghanistan, US commanders have also expressed concern about Islamic State fighters moving into the country and gaining recruits from within the Taliban.