here a list of "enemies":
and remarked that:
the first three are World War II;
the fourth is Cold War and maybe World War III;
the fifth and sixth must be post -WWIII?
In fact, as I am reminded by rereading the series out of order, the Americanist Party was the collective villain of the preceding installment of the Psychotechnic History - so that is where they came from. The first and second installments are linked by the character of Fourre; the second and third by their common reference to Americanists. In these opening episodes of this future history series, groups with incompatible philosophies fight to determine the course of their future history.
And any series by Poul Anderson has a rich vocabulary.
While investigating the Americanists, the Un-Man "...painted his fingertips with collodoin." (The Psychotechnic League, p. 31)
"...he inserted a few cubic cenitmeters of levinite [?]..." (p. 34)
"He had only time to see the stet-gun [?] within..." (ibid.)
"'Mr. Wade is...Rodney Borrow, Exogene Number -'" (p. 37)