U.S. Defense Secretary Ash Carter has said that a decision giving U.S. commanders more authority to work with Afghan troops and attack Taliban militants will maximize the effectiveness of U.S. troops in Afghanistan.
Carter also said progress by the Afghan government in the fight against corruption is "central" to continued international support for Afghanistan.
Carter made the remarks at a July 12 press conference with Afghan President Ashraf Ghani during a previously unannounced visit to Afghanistan.
He also was scheduled to meet with Afghanistan's chief executive officer, Abdullah Abdullah, and the top U.S. military commander in Afghanistan, General John W. Nicholson.
Nicholson said after meeting with Carter that he is making daily use of the expanded authorities granted to him in June by President Barack Obama.
The visit comes shortly after U.S. President Barack Obama announced that the United States would keep around 8,450 troops in Afghanistan in 2017 instead of reducing their numbers to 5,500 as previously planned.
Nicholson said 3,000 U.S. troops will work as advisers in Afghanistan, 2,150 will be involved in counterterrorism operations, and 3,300 will work in a supporting role for Afghan security forces.
Along with its troops taking part in NATO's advisory-and-assist mission, the U.S. has special operations forces in Afghanistan for counterterrorism missions.