Last Updated 12:37 p.m. ET
WASHINGTON - Vice President Joe Biden paid tribute to what he calls a "9/11 generation of warriors" in Sunday remarks marking the 10th anniversary of the September 11 attacks.
Speaking at the Pentagon, which was heavily damaged in the 9/11 attacks, Biden said, "Never before in our history has America asked so much over such a sustained period of an all-volunteer force."
He said the "9/11 generation ranks among the greatest our nation has ever produced."
Defense Secretary Leon Panetta observed a moment of silence at 9:37, marking the time a jet struck the Pentagon 10 years ago. He paid tribute to the 6,200 members of the U.S. military who have died in the Iraq and Afghan wars.
President Barack Obama is expected to visit the Pentagon later, after returning from New York and Shanksville, Pa.
Defense Secretary Leon Panetta is highlighting the contributions of the military in helping avert a repeat of the terrorist attacks of Sept. 11, 2001.
After a moment of silence at 9:37 am EDT - the exact time the Pentagon was hit by the hijacked jetliner a decade ago - Panetta paid tribute Sunday to those who have served in uniform in the decade since.
He said more than 6,200 members of the U.S. military have died in the wars in Iraq and Afghanistan since the Sept. 11 attacks.
Vice President Joe Biden also attended the remembrance ceremony, and President Barack Obama plans to lay a wreath at the Pentagon's 9/11 memorial later Sunday.