Source CSPAN

On September 10, 2001, Donald Rumsfeld made the shocking announcement that the Pentagon "couldn't track" $2.3 trillion of its transactions. "Iroquois" observes, "What's interesting to me is that he made his press release on a Monday. In DC, I always see bad news given on a Friday, usually late in the afternoon on Friday. The exception, of course, would be when someone happens to know that there is a far bigger story coming out."
And we know that Flight 77, allegedly piloted by an incompetent, made an aerobatic, spiraling descent over Washington, effecting a 270-degree turn to strike the Pentagon from a western approach at ground level. The side struck was the only one with an exterior wall hardened against attack, and was relatively empty while renovation continued.
Relatively. The unfortunate construction workers perished outside, but who were the expendables within?

 From The Pittsburg Post Gazette, December 20, 2001: "One Army office in the Pentagon lost 34 of its 65 employees in the attack. Most of those killed in the office, called Resource Services Washington, were civilian accountants, bookkeepers, and budget analysts. They were at their desks when American Airlines Flight 77 struck."

I may point out that this particular section of the Pentagon had just been "fortified" against such attacks and that this particular department was responsible for tracking the missing $2.3 Trillion, what a coincidence!

Note: Look at the length of the video, it's 9:11!