"By the summer, we should have around 12,000 forces in the country," Jens Stoltenberg said addressing a press conference ahead of NATO Foreign Ministerial meeting.
He said that no decision for a further reduction has been taken, adding all of NATO's steps will be conditions-based.
"NATO will maintain its commitment to long-term peace and stability in Afghanistan," Stoltenberg said. "The situation remains difficult."
He said that now is the time for the Taliban and all political actors to play their part.
"All parties need to engage constructively honour their commitments, and ensure intra-Afghan negotiations can start."
He said that the Afghans have to take responsibility for their own future.