I remember it mentioned the book but I never read it.
When they had the Looking Glass going after AF1, I figured they had gone total Lefty. I don’t know if that was in the book, admittedly.
I had to check. The Looking Glass is pursuing the E4 but since Darren McGavin is the acting President it would change call signs to AF1, I believe, instead of NAOC (or in addition).
Of course the real President is still alive and.....ah it’s just a movie, so....