Were procedures changed on June 1, 2001 about intercepting off-course airplanes?

Is it true that before June 2001 it would have been official procedure to intercept planes and shoot them down in a scenario such as the one of 9/11 without needing high level approval but after that date approval was needed and not given on 9/11?

Former Governor of Minnesota Jesse Ventura writes in American Conspiracies: Lies, Lies, and More Dirty Lies That the Government Tells Us:

Between September 2000 and June 2001, on 67 different occasions fighter jets were sent to intercept aircraft that had lost radio contact or their transponder signal or were flying off course, usually within ten minutes of any sign of a problem. (Contrary to what some people think, presidential approval wasn’t needed to intercept or even shoot down an aircraft.) Then, on June 1, 2001, the existing hijacking response procedures were changed to require approval by the secretary of defense before responding to a situation with lethal force. And when the call came into the Pentagon on 9/11, nobody answered the phone!

Is it true that before June 2001 it would have been official procedure to intercept planes and shoot them down in a scenario such as the one of 9/11 without needing high level approval but after that date approval was needed and not given on 9/11?