Many works of sf describe future military conflicts, e.g.:
several works by Poul Anderson, including Mirkheim, The People Of The Wind and Ensign Flandry in his Technic History;
the Man-Kzin Wars sub-series of Larry Niven's Known Space future history series;
Jerry Pournelle's Codominium future history series and its War World sub-series;
Robert Heinlein's Starship Troopers;
Joe Haldeman's The Forever War;
Pournelle's There Will Be War anthology series;
SM Stirling's Draka series.
I describe Heinlein and Pournelle although not Anderson, Niven, Haldeman or Stirling, as "militarist" and am asked, "What is militarism?" so let's clear this up. My initial response is that I see the "militarist" authors as not merely describing but also glorifying war. "Glory..." is explicit in the concluding line of Starship Troopers.
That is my initial response but there is room for discussion. In any case, an initial use of a word might be followed by its more considered use. We might sometimes consult a dictionary. The dictionary definitions (plural) of a word indicate the ways in which that word had been used in the period before the dictionary was published. People continue to use words in slightly different senses. A later edition of a dictionary will include new words and new meanings of old words and will sometimes inform us that an older meaning has become "archaic." Languages continue to change as long as they are spoken. Understanding all this prevents pointless arguments about the one true meaning of any particular word.
My 1983 Chambers Dictionary presents several meanings of "militarism":
"an excess of the military spirit";
"domination by an army...
"...or military class...
"...or ideals";
"belief in such domination";
"a tendency to overvalue military power...
"...or to view things from the soldier's point of view."
A wide range of uses, some certainly applying to the authors under discussion.