The names of those who perished at the Pentagon 20 years ago on 9/11 were read aloud at the headquarters on Saturday during a memorial ceremony.

Secretary of Defense Lloyd Austin said it is up to the U.S. to keep their memories alive.

"It is our responsibility to remember, and it is our duty to defend democracy,” he said. “We cannot know what the next 20 years will bring. We cannot know what new dangers they will carry."

A total of 125 names were read.