Here is the exchange I had with Virginia Anderson, one of the authors of the book, but not the author that wrote the line in question. I wrote the author who did, Robert Weir, but he did not respond to my query.
Dear Dr. Anderson,
My son and I were studying your book, The American Journey (sixth edition), and came across the following quote on page 156 of chapter 6:
"Mr. President, your doctrine of preemptive [sic] war is a failed doctrine."
and we were curious about the use of [sic]. A google search of this phrase, spoken by George F. Regas, turned up several hits, none of them including [sic]. At first we thought preemptive might have been an erroneous spelling, or even a malapropism, but dictionaries validate the word.
If you wouldn't mind, a short, edifying explanation? Thank you for your time.
Dear Mr. Kennedy,
Many thanks for your email. I must confess that I am also puzzled by the "[sic]." I took over the revisions of chapters 5 and 6 of the textbook from Prof. Robert Weir beginning with the 6th edition, so he was actually the author of that "From Then to Now" essay. My best guesses are either that he thought the word should be hyphenated (pre-emptive), although the dictionaries I looked at didn't include a hyphenated version as the preferred one. Another possibility is that the so-called Bush Doctrine occasionally referred to "preventive war," and so that could be why Prof. Weir included the [sic].
I regret that I cannot give you a more definitive answer. The puzzle won't appear in the 7th edition, since I am writing a new "From Then to Now" essay for the 6th chapter.
Again, thanks for your question.
Virginia DeJohn Anderson
Dept. of History
University of Colorado
Boulder, CO 80309-0234