NATO Secretary General Jens Stoltenberg is in Kabul on an unannounced trip to visit troops and meet with the country's new leaders.

Stoltenberg, who took over as the head of the Western alliance on Oct. 1, visited a training center for Afghan special forces on Thursday, where he told Afghan troops that NATO will continue its support once its combat forces withdraw at the end of the year.

NATO and the United States are withdrawing combat forces from Afghanistan at the end of the year, after 13 years of fighting the Taliban insurgency.

A residual force of up to 12,000 U.S. and NATO forces will remain to provide training and backup for Afghan forces.

Afghanistan has a total of 350,000 security forces.