Defense Secretary Robert Gates says the accidental killing of civilians in Afghanistan has become one of the military's greatest strategic problems in the faltering war, AP reported.
Gates says it will take another day or two before officials release their investigation into an early May battle and airstrikes in which dozens of Afghan civilians were killed.
Officials have already said some mistakes were made and that procedures were not strictly followed in the operation.
But Chairman of the Joint Chiefs of Staff Admiral Mike Mullen says he has seen nothing in the investigation that seems to warrant disciplinary action against the U.S. forces involved.