My TiVo recently captured Spike TV’s rerunning of Star Trek: Deep Space 9’s two part “The Way of the Warrior” episode. It’s far from great, but for present day circumstances it’s an interesting example of a 1995-vintage portrayal of the concept of preventive war — what Bush has tried to label “preemption.” The basic philosophy behind preventive war is that there might be a country somewhere that hasn’t attacking you, and that as far as you know has no immediate plans to attack you, and, indeed, is weak and poses no threat to you. But, you think, the other country (or its government) is just rotten and might attack you one of these days and might get stronger in the future, so you need to attack them now.
In the episodes in question, various Alpha Quadrant cultures are all in something of a cold war dynamic with a race of shapeshifters from the Delta Quadrant. Since the shapeshifters can convincing imitate all manner of humanoids, there’s naturally a paranoid atmosphere. At this point, the government of the Cardassian Empire falls apart and a new civilian regime comes to power. The Klingons decide that maybe the change of regime reflects a shapeshifter plot so they decide to invade!
Various consequences spill off from this. But the important point, just as a cultural observation, is that none of the good guy characters on the show so much as consider the idea that the Klingons are behaving in an acceptable manner. The writers clearly just took it for granted that a pile of vague circumstantial evidence that some people are maybe in league with the enemy doesn’t count as a good reason to start a war. And my general impression is that that’s just how it was in the United States. The view that it might sometimes be acceptable to wage wars of aggression on a mix of suspicion and trumped-up pretext was a totally marginal view.