A major nuclear war gamer/theorist, A. Wohlstetter, was a Trotskyist in the thirties, as was scary mofo, James Burnham, who did write for Partisan Review. (See for example, his piece, "Lenin's Heir, " from around 1940.)
Social Democrats, USA, in the early to mid-70's would have talks by such as Walter Laqueur and Richard Perle. (Perle was a staffer for Scoop Jackson.)
Look up a South End Press book by Jerry Sanders on the Committee for the Free Worldthat Rummy was in along with Partisan Review ex-Trot, James T. Farrell. Alan Wald wrote a book on Farrell, well worth a look.
Also, see a symposium in Commentary on, "Liberal Anti-Comunism Revisted."