Thanks, Mr. Brancato, for the thoughtful reply. Yes, the quote we remember best - and it may not have been in Mr. Douglas' book - was JFK's thinking out loud that if there was ever a coup against him, his administration, it would be by the Military.
The armed forces are difficult to investigate for their alleged central role in JFK's murder because they destroyed - from our understanding - all of Lee Oswald's records surrounding the assassination.
Then again, if memory serves, a fire destroyed nearly 14 million U.S. personnel files in 1973. We haven't read enough to conclude whether it was set intentionally, or, not - but it certainly caused a lot of heartache among vets who were due benefits.
*Also, thank you Mr. Thomas for providing much of the digging into the Pentagon involvement angle - the pent-angle so to speak.