American society has changed in many ways since 9/11: some changes are easy to see and others are less visible.

Bruce Hoffman, a professor of security studies at Georgetown University, was working at the Rand Corporation across from the Pentagon, and was at his offices when the hijacked plane crashed on 9/11.

The World spoke to Hoffman just hours after the September 11, 2001 attacks.

Listen to Bruce Hoffman’s September 11, 2001 interview