It's unlikely that the killing of 16 Afghan civilians on Sunday, allegedly by a U.S. Army staff sergeant, will drastically alter the course of the war.
U.S. and NATO strategy calls for a sizable contingent of international troops to stay in Afghanistan until 2014, with residual support after that. That timetable is unlikely to change.
But the task U.S. forces face in trying to stabilize the country could well be made more difficult by the shootings.