When did he know about it?

Pull the slider to about 3:00 and find out.

ABC News reporter John Cochran told ABC's Peter Jennings, "He got out of his hotel suite this morning, was about to leave, reporters saw the White House chief of staff Andy Card whisper into his ear, then reporters said to the President 'do you know what's going on in New York'? - he said he did and would have something to say about it later."

For more info and Bush's answer to this question