“We recognize that our troops sometimes do criminal acts. And sometimes heinous acts, but we will hold them accountable," he said. "We will never give them a pass, but we will be the ones who are in charge because there are just too many countries around the world with too many different legal systems to allow our troops to be caught up in things that could be politicized, and that could often involve legal systems that are not as well developed and penal systems that are not as well developed."

Whether U.S. forces would be allowed to enter Afghan homes while pursuing militants is another sensitive issue.

U.S. officials have expressed confidence that Afghans will accept a bilateral security agreement, in part because many believe that peace beyond 2014 depends on the presence of U.S. troops.

Continuing presence

Afghan security forces are developing, but still have a long way to go before they can stand up on their own against insurgents. U.S. officials are talking about leaving a force of as many as 12,000 troops to train, advise and assist the Afghans. The number depends on how stable Afghanistan remains, how far reconciliation efforts go, the strength of Taliban insurgents, the presence of al-Qaida militants, and the level of cooperation from neighboring Pakistan.

Hagel said any decision to stay will have to be at the invitation of the Afghans, and that should come soon.

"Obviously the sooner the better," he said. "We all need time to plan, to prepare."