The number of U.S. military deaths in Afghanistan this month now stands at 66, making August the deadliest month for American soldiers since the war on terror began.
Nearly half the troops killed this month died when the Taliban shot down a Chinook helicopter Aug. 6.
Violence continues across Afghanistan despite the U.S.-led efforts to drive out the Taliban.
Afghan President Hamid Karzai has set the end of 2014 as the target date for Afghan police and soldiers to take the lead in protecting and defending the country.
President Barack Obama's order to withdraw the 33,000 additional troops he sent to the war has already started.
"As our mission transitions from combat to support, Afghans will take responsibility for their own security and the longest war in American history will come to a responsible end," Obama said Tuesday at an American Legion convention. "For our troops and military families who have sacrificed so much, this means relief from an unrelenting decade of operations."
This year, 403 international service members, including at least 299 Americans, have been killed in Afghanistan.