In Afghanistan's rugged mountains and rocky deserts, American service men and women paused in their anti-terrorism fight Wednesday and stood in silence to honor those who died in the Sept. 11 attacks.

"There is no other place I would want to be," Spc. Daryl Appling said after a memorial ceremony at Kandahar Air Base in southern Afghanistan. "I wanted to be here because there is a sense of productivity to what we're doing."

At Bagram Air Base, the U.S. military headquarters north of Kabul, the Afghan capital, troops stood in tan fatigues, their heads bowed, in a 20-minute ceremony led by Lt. Gen. Dan K. McNeill, commander of coalition forces.

"Those of you who are here on this battlefield, you're the heroes and heroines of today," McNeill told more than 200 troops. "It is you who are relentlessly taking this fight to the enemy. It is you to whom your nation owes it's gratitude.

In Bamiyan, a mountainous province of central Afghanistan, U.S. special forces troops awoke before dawn to raise the Stars and Stripes. One soldier sang the "Star-spangled Banner" as the men saluted the flag as it fluttered over the valley where giant Buddha statues stood for 15 centuries before they were destroyed by the Islamic fundamentalist Taliban regime last year.

At Kandahar, U.S. troops from the Army and Air Force rushed to finish their daily tasks to make time for the ceremony which drew about 500 people.

Many wiped tears from their eyes at the end of a moment of silence. They later gathered around a permanent bronze plaque honoring the victims of the al-Qaida suicide hijackings.

Lt. Nicole Casanassima, 23, said the ceremony had special meaning because she was a New York native. "I'm glad I'm here," she said. "I feel like I'm doing something to help."

In Bagram, troops were reminded of the danger of their mission. Early Wednesday, a gunman fired at a guard tower on the northwestern edge of the base. There were no U.S. casualties, but the Americans returned fire and wounded the gunman.

Gates leading into the Bagram base were closed briefly after the incident.

In southeast Afghanistan, one of the main fronts in the hunt for al-Qaida and Taliban remnants, two rockets were fired at the airport in Khost, where U.S. troops are based.

The rockets exploded in an open field at dawn just east of the airport, said Mohammad Khan Gorbuz, spokesman for the provincial governor. Rockets have frequently been fired in the vicinity of U.S. troops in the Khost region.

Apart from the anniversary ceremonies, it was business-as-usual for soldiers.

"Pursuing the war on the anniversary of the attack is what makes today a big day," said Lt. Col. Tim Strasburger, an A-10 jet pilot permanently based at Pope Air Force Base outside Fayetteville, N.C. "There isn't a place I'd rather be or a job I'd rather be doing."

The A-10s are used to provide air cover for ground troops.

About a mile along the flight line, more than 100 soldiers from the 82nd Airborne Division practiced getting on and off the back of a Chinook helicopter.

"A lot of us are thinking about it, but it's really just like any other day," said Pvt. Sean Bargmann, a 23-year-old from Gilman, Ill. "We've got to act like anything could happen today, because it could -- look at what happened this morning," he said, referring to the sniper shots fired on the base guard post.

Some Air Force personnel marked the day with an old tradition -- writing messages on bombs and missiles carried by the A-10s.

"In memory of 9-11-2001," read one message on a Maverick missile.

"To the Taliban, we come with gifts," read another.