The ministers of the 30 NATO member states will on Wednesday and Thursday hold their highest-level talks since US President Joe Biden took office vowing to work closer with allies after four years of tensions under Donald Trump.

Top of the agenda for the virtual conference will be the fate of the alliance's 9,600-strong support mission in Afghanistan after Trump struck a deal with the Taliban to withdraw troops.

The deployment's future hinges on whether Biden agrees to stick to a May deadline to pull out foreign forces or risks a bloody backlash from the Islamist insurgents by staying put.

"While no ally wants to stay in Afghanistan longer than necessary, we will not leave before the time is right," Stoltenberg told a media conference.

"Ministers will continue to assess the situation on the ground and monitor developments very closely."

Biden's administration says it is reviewing the deal, and the Pentagon has accused the Taliban of not fulfilling promises that include reducing attacks and cutting ties to insurgent groups like Al-Qaeda.

Defence ministers are not expected to make a concrete announcement on the deployment's future at their meeting.

NATO allies want the US to consult more closely with them after feeling sidelined when Trump cut US troop numbers to 2,5000 in January, their lowest figure since the start of the war in 2001.

Taliban violence has surged in recent months amid stuttering peace talks with the Kabul government. The group has warned NATO ministers not to seek a "continuation of occupation and war".

"The Taliban must reduce violence, negotiate in good faith and live up to their commitment to stop cooperating with national terrorist groups," Stoltenberg said.

"Our common goal is clear. Afghanistan should never again serve as a haven for terrorists to attack our homelands."

A study mandated by the US Congress has called for a delay in the pullout, warning it would effectively hand the Taliban a victory.