The top U.S. military officer, the chairman of the Joint Chiefs of Staff, is in Afghanistan to meet with American and Afghan officials and assess the number of U.S. troops who should remain in the country to train Afghan soldiers after next year.
General Martin Dempsey's previously unannounced trip to Kabul began Saturday. He also is expected to visit with American troops in the field, as part of the effort to plan the future U.S. role in Afghanistan following the withdrawal of all combat units by the end of 2014.
It is not clear yet how many foreign troops will remain to assist the Afghan army in handling the country's still-volatile security situation. Experts estimate the United States will keep between 6,000 and 20,000 troops in Afghanistan as trainers.
Meanwhile, NATO says an explosion in southern Afghanistan Saturday killed three of its service members and two civilians working with the coalition on Saturday.
None of the victims was immediately identified.