I'd read an account of circumstances surrounding the "Thoughts for the President’s Consideration” memo several years ago but did not make a connection to 9/11. Having researched this further, here is one essay as a point of discussion in the 9/11 community and at large.
PS for those who have followed the historic parallels between Presidents Lincoln and Kennedy, it is uncanny that Operation Northwoods was also presented to the 35th administration.
-MG