By his own account, was 9/11:
Bodies and their shadows often concur, but the wreckage of our skies confirm separations. Dick Cheney was in the Presidential Emergency Operations Center (PEOC) with his wife Lynne on that morning, before Secretary of Transportation Norm Mineta arrived. Mineta gave the only sworn eyewitness testimony regarding Cheney's activities during the terrorist operations:WALLACE: Highest moment the last eight years?
CHENEY: Hmmm. Highest moment in the last eight years. Well, I think the most important, the most compelling, was 9/11 itself, and what that entailed, what we had to deal with. The way in which that changed the nation, and set the agenda for what we had to deal with as an administration.
WALLACE: And I assume that was also you're lowest moment.
CHENEY: Yeah...sure.
No, I was not [aware that shoot-down orders had been given]. I was made aware of it during the time of the airplane coming into the Pentagon. There was a young man who would come in and say to the Vice President, "The plane is 50 miles out...the plane is 30 miles out..." And when it got down to, uh, the plane is 10 miles out, the young man also said to the Vice President, "Do the orders still stand," and the Vice President turned, whipped his neck around and said, "Of course the orders still stand! Have you heard anything to the contrary?"Orders? What orders? Presumably, they pertained to either shooting down the incoming planes or not. Subsequently, despite being integral to the timeline and tragedy, the implications of Mineta's testimony were strenuously avoided; there are no records of shoot-down orders or otherwise. They were suffocated in the bassinet of bureaucracy, yet Cheney regards 9/11 and what followed as his best time in office. And if I were in the White House bunker on that day, in command and responsible for the deaths of Americans no matter what I decided, it would not roll it off the top of my head as a "highest moment."
And what about the "young man?" How was he keeping Vice President Cheney minuted? He must have been scurrying back from the FAA-integrated Secret Service operations screens in the PEOC bunker. The Secret Service was monitoring the hijacked flights during Global Guardian, a yearly threat-response exercise, and its 2001 airborne subset Vigilant Guardian, a live-fly wargame focused on inter-agency response to hijacked commercial airliners (disputed by answers to the 9/11 Commission, but previously center-pieced in an Air Force powerpoint presentation, Amalgam Virgo 01). By FAA procedure, a passenger jet which turns off its transponder immediately appears on military radar as a potential threat. Any commercial flight which did so that morning would have looked like an additional bogey to the military.
The notion that 19 non-pilots evaded the defenses of the most sophisticated airspace in the world for two hours begs credulity, as does lack of forensic evidence and transparency. This is partially mitigated by the report that five of the hijackers received training at US military bases in the 1990s (source MSNBC/Newsweek article). At least some of them could fly. But they chose the day from caves in Afghanistan when the US Air Force was conducting an anti-hijack exercise which involved every major security entity in North America (read the powerpoint)? That strains credulity into a double-hernia.
I want my suspicions and all my body's senses (for I drove by the twin towers at 8:31 on 9/11, was there for its aftermath, and my former boss and co-workers died for having breakfast in Windows on the World) to be wrong, wrong, wrong. I and 70% of my fellow New Yorkers are biased. If you can downplay or disagree, please send us contravening facts to set our minds at ease. We are all passengers in this car, and like the EPA says, your reality may differ.
The media provoked this post by the offence of giving air-time to a non-convicted architect of horrors, which none likely to come here would dispute. Bush and Cheney ordered programs of torture based on nothing more Constitutional than a Berkeley lawyer's opinion (known as "Dr. Yes" in the White House). My point is about burdens of evidence, that they're not on you or me but on a government which failed to provide them. Then stonewalls. Then gives interviews, and gloats.
If you find footage of a plane flying into the Pentagon, one of the buildings with the highest monitoring of closed-circuit TV cameras in the world, you'll be my Santa Claus. Google away. Meanwhile, evidence was provided by a most credible witness in congressional testimony about a man's decision-making on that morning which killed Americans. We don't know what decision was made, but incinerations and all the sins which followed from it are broadcast as the highest moment. May he never have another.

