August has been the deadliest month for U.S. forces in Afghanistan, since the conflict began nearly a decade ago.
There were 66 troop deaths this month. That tops the recorded 65 troops killed in July 2010. Nearly half of this month's American deaths came from an insurgent attack on a helicopter, which left 30 dead.
Some 10,000 U.S. troops are scheduled to leave Afghanistan by the end of this year.