Although the alliance put off making a decision on the fate of NATO's 9,600-strong support mission, they opted to expand a training mission in Iraq to "around 4,000" personnel.
NATO Secretary General Jens Stoltenberg has said the alliance had made "no final decision" on the future of its Afghanistan mission, as new US President Joe Biden weighs pulling out troops.
While defence ministers held off on making that call on Thursday at a two-day virtual conference, they did decide to expand a NATO training mission in Iraq from 500 to "around 4,000" personnel.
The fate of NATO's 9,600-strong support mission in Afghanistan was top of the agenda after former US leader Donald Trump struck a deal with the Taliban to pull troops out.
Biden's administration is reviewing whether to stick to a looming May 1 deadline to withdraw or risk a bloody backlash from the insurgents by staying.
In Washington, calls are mounting for the United States to delay the final exit or renegotiate the deal to allow the presence of a smaller, intelligence-based American force.
After two decades of Western military intervention and hundreds of billions of dollars in investment, NATO countries are reluctant to heed the deadline and risk undermining progress towards democracy.
US stance on withdrawal
US Secretary of State Antony Blinken discussed on Wednesday with Afghan President Ashraf Ghani an ongoing review of US strategy in Afghanistan, with the top American diplomat reiterating support for the peace process, the State Department said on Thursday.
Blinken told Ghani that the United States is committed to a peace deal that includes "a just and durable political settlement and permanent and comprehensive ceasefire," according to the statement from State Department spokesperson Ned Price.
The Taliban agreed in the February 2020 deal to reduce violence and to stop hosting Al Qaeda fighters or allowing them to raise funds, recruit and train in Afghanistan.
US and European officials have said the Taliban have not met their commitments and that surging violence does not create conditions for progress toward peace.
The insurgents say there are no Al Qaeda fighters in Afghanistan. They have indicated they will resume attacks on foreign troops if Washington fails to adhere to the May 1 pullout deadline.
Stalling peace talks
"We have made no final decision on the future of our presence," Stoltenberg said at a news conference.
"But as the May 1st deadline is approaching, NATO allies will continue to closely consult and coordinate in the coming weeks."
Stoltenberg insisted the Taliban must live up to commitments under the deal with the US, including making progress in peace talks with Kabul, reducing violence and cutting ties to "international terrorist groups."
"NATO's goal is to ensure that Afghanistan never again becomes a safe haven for terrorists that would attack our homelands," he said.
Attacks in Afghanistan, including a bomb that killed the deputy governor of the capital Kabul in December, have prompted members of the US Congress and international rights groups to call for a delay to the pullout, agreed when Donald Trump was US president.
Earlier on Thursday, two lecturers at Kabul University were killed when a bomb attached to the car they were traveling in went off. No group immediately claimed responsibility.
"We are faced with many dilemmas, and there are no easy options," Stoltenberg said.
"If we stay beyond the first of May, we risk more violence, more attacks against our own troops ... But if we leave, then we will also risk that the gains that we have made are lost."
US Defense Secretary Lloyd Austin promised to consult with allies and partners on the way forward, Stoltenberg added.
Iraq training mission
On Iraq, defence ministers agreed to bolster a NATO training mission aimed at strengthening the country's military as it looks to curb the resurgence of the Daesh group.
"The size of our mission will increase from 500 personnel to around 4,000," Stoltenberg said, adding that the increases would be "incremental."
"Training activities will now include more Iraqi security institutions, and areas beyond Baghdad."
Stoltenberg insisted that the mission was being carried out "at the request of the Iraqi government."
"It is carried out with full respect for Iraq's sovereignty and territorial integrity," he said.