Eight US troops were killed in battle after tribal militia attacked two combat outposts in a remote area in eastern Afghanistan.
It is the deadliest battle for US troops in more than a year.
The battle took place in an area from which US forces had already announced plans to withdraw as part of the strategy to focus forces on population centres.
Saturday's attacks were launched by militia in Nuristan province from a local mosque and a nearby village on two joint NATO and Afghan outposts.
The NATO troops in the area are American.
