"We agreed to sustain the presence of our Resolute Support Mission… in Afghanistan during 2016. This will be approximately 12,000 troops," Stoltenberg said.
The US-led NATO combat force withdrew from Afghanistan in December 2014. Some 12,000 personnel from NATO remain in the country as part of the alliance's Resolute Support non-combat mission, conceived to provide training for the Afghan security forces and institutions.
Stoltenberg also said that some 7,000 service personnel from the United States will take part in NATO non-combat mission in Afghanistan in 2016.
"The US provides around 7,000 troops of the troops in the Resolute Support Mission. And then non-US countries, non-US NATO allies and partners provide approximately 5,000," Stoltenberg said at a meeting of NATO foreign ministers.
In October, US President Barack Obama announced that US military troops would not be leaving Afghanistan by the end of 2016, as had been previously planned. According to Obama, a contingent of 5,500 US soldiers would stay in the country after 2016.
Afghanistan continues to be in political and social turmoil as several militant groups take advantage of the instability in the country that has persisted since the 2001 US-led invasion.