Just what was this E-4 actually doing

[tor lives]

Now while I am not one to encourage the conspiracy nuts, (9/11 was in inside job, faked moon landings, chemtrails, etc ), I have always wondered just what the hell this E-4 was doing on the morning of 9/11.
https://www.youtube.com/watch?v=SMK5bmdAEHc
It is especially intriguing that the Pentagon emphatically denied that it was a military aircraft when it is quiet obviously and E-4.