Alas, the complete, multivolume edition of the Pentagon Papers (also known as the "Gravel edition," because Sen. Mike Gravel, D-Alaska, put the whole thing in the Congressional Record) is out of print. If you can find a used copy, check out Volumes II and III, particularly the memoranda preceding the Rolling Thunder bombing campaign of 1964. I go into the issue of Vietnam and "sending signals with force" in Chapter 23 of my 1983 book, The Wizards of Armageddon.