Utilizes an innovative technique: scenes spoken in Russian begin in Russian and after a couple of interchanges segue to being spoken in English, avoiding either usual extreme of subtitling or dubbing into English.
John Huston said of this film in his auto-biography 'An Open Book': "I thought 'The Kremlin Letter' had all the makings of a success... The book by Noel Behn had been a best-seller. It had, moreover, all those qualities that were just coming into fashion in 1970 - violence, lurid sex, drugs. The cast was exceptionally strong... and the performances couldn't have been bettered. It was extremely well photographed [by Edward Scaife] - there was a virtuosity, a shine to it. Gladys Hill and I wrote the script, which I considered quite good, though in retrospect it was perhaps overcomplicated."
This movie was made and released about four years after its source novel of the same name by Noel Behn was first published in 1966. This was the first ever adaptation for cinema of a work by Behn. The only other one is The Brink's Job (1978) based on Behn's book 'Big Stick Up At Brink's'.
French crime film auteur Jean-Pierre Melville described this film as "magistral" (masterly or magisterial). UCLA academic Bob Hudson's article in the journal 'Lingua Romana : a journal of French, Italian and Romanian culture' (4, 1, Fall 2005), entitled "J.-P. Melville's Quest for the Absolute: Persistent Perfectionism and Realistic Obsession in His 'Last' Films", states that Melville "...saw it as establishing the standard for cinema" and said that his quest in films was to achieve such grandeur.
John Huston performed a number of roles on this movie. Huston was director, script co-writer, an uncredited producer and as an actor did a cameo. Huston made this spy movie not long before he would helm another espionage film, The MacKintosh Man (1973).
Initially, Steve McQueen was offered the part of "Charles Rone", but turned it down. John Huston also considered Warren Beatty and Robert Redford for the part before signing Patrick O'Neal, whom he had strongly considered as a replacement for Montgomery Clift in his earlier film, "Reflections In A Golden Eye" prior to his hiring Marlon Brando instead.