Night Flight from Moscow has as a premise that a Russian Top Spymaster (Yul Brunner) defects to the West while in France and delivers the Western Intelligence services with information on possible traitors in high places of the Western Security apparatus. While the CIA and other agencies are collating and verifying the given information somebody bumps off the suspected turncoats. (who that is, is shown far too early in the movie)
Now as a premise it might have been a great thriller. The movie, however, bogs down in explaining and glorifying at length the workings of the CIA, which is a pity, as the ending is somewhat "forced" to bring the movie to a conclusion. And the CIA spymaster (Henry Fonda) already knew everything.(???) You then wonder how he let the murders and this "game" go on for so long.
As a movie reflecting its time (60's and 70's) it is a perfect illustration of the machinations of the then security services and the politics behind spying.
So from that point of view it is a perfect child of its time.