American troops in Afghanistan donned shorts and sneakers Friday to run in memory of the Sept. 11, 2001 attacks, as they fight a war that was born of that day but now faces waning public support.

About 1,000 service members ran 9.11 kilometers (about 5.5 miles) at the main U.S. base, both to commemorate the anniversary and remember troops who have died in nearly eight years of fighting.

The U.S. and its allies first invaded Afghanistan in October 2001 to oust the Taliban regime for sheltering al-Qaida leaders who planned the attacks. The Taliban were quickly routed, but the militants regrouped and have mounted an increasingly strong insurgency over the past three years.

Organizers of Friday''s race, which also was held at two other bases, called it an act of defiance against insurgents who have killed more American troops this year than in any other since the beginning of the conflict. August was the deadliest month for U.S. troops so far, with 51 killed.

"Our soldiers are running in the heart of Taliban territory, where the attacks on America were planned," a military statement said.

Soldiers in the early morning run at Bagram said their mission has grown beyond those autumn days of 2001 when priority No. 1 was to get al-Qaida leader Osama bin Laden.