Why Weren't We Prepared?

There was an unsettling footnote to the September 11 ceremonies. Buried amidst the ceremonies was a story that two F 16's were sent out to ram the plane that eventually went down in Pennsylvania before it reached Washington, DC. The reason? We did not have any planes armed and on alert in case of an emergency. How is this possible? During the cold war, we were on a constant state of readiness. How could this have become lax? These aren't rhetorical questions. I'd like to hear from our government to answer why this happened and how it has been corrected. We need to know. American needs to know.