Afghanistan has made significant progress on building its security forces, Wardak said, but will continue to need U.S. help as it moves toward and beyond the transition.

There are currently nearly 100,000 U.S. troops in Afghanistan, but President Barack Obama said that number will begin to come down in July. Officials expect a gradual withdrawal during the next four years, with some support troops remaining even after the end of 2014.

The United States is scheduled to complete a similar transition in Iraq this year. There, U.S. combat operations ended last August and all the troops are to be out by the end of the year.

U.S. officials hope Iraq will ask for some small continued presence - like the one they expect in Afghanistan - to provide air power and support services, and to act as a stabilizing influence to balance sectarian tension. But there has been no discussion toward any such agreement, partly because the new Iraqi government has not yet named a defense minister.