Germany, Turkey and Italy are set to maintain their deployments in Afghanistan at current levels, a senior NATO official told Reuters on Monday.
The announcement comes one week after the U.S. government decided to prolong its 14-year military presence there.
The Taliban's recent takeover of a provincial capital has raised concerns about the abilities of Afghan security forces. The United States and its NATO allies now say events, rather than timetables, must dictate gradual troop reductions.
"We should make any changes on our troop structure based on conditions on the ground, not on schedules," NATO's top commander in Europe Philip Breedlove told Reuters. "Other nations are already ringing in that they are committed."
NATO countries will continue alongside the nearly 10,000 U.S. troops in Afghanistan, Breedlove added. Discussions of exact numbers are still continuing.
Germany, the top NATO-country contributor, has around 850 troops in Afghanistan, followed by Italy with 760 and about 500 for Turkey, according to the latest NATO data.
Unlike the United States, NATO has never set an end date to its support training mission in Afghanistan. The 6,000-strong force includes troops from some 40 countries, including NATO members, the United States and their allies.
A formal decision is expected to come at NATO's next meeting of its foreign ministers in Brussels in early December, another official told Reuters.
Although Afghan forces have recaptured the strategic northern city of Kunduz, its brief fall to the Taliban last month underscored concerns about the capabilities of Afghanistan's security forces.
A U.S. military strike in Kunduz that hit an Afghan hospital run by Doctors Without Borders, known internationally as Medecins Sans Frontieres (MSF), also generated international outrage and emphasized the consequences of pulling out of a fragile country too quickly.
President Obama had aimed to withdraw all but a small U.S. force before leaving office by training and equipping local forces to battle the Taliban.
Instead, he'll keep the current force of 9,800 through most of 2016 before beginning to trim levels from 2017.
Washington has spent around $65 billion on training and arming the struggling Afghan security forces of about 350,000 personnel.
U.S. Defense Secretary Ash Carter is preparing a U.S. funding request to sustain those troops in 2017 "and beyond."