A thriller without a villain or even an antagonist. Impressive.
It's true, if you think about it. The Soviets aren't the villain in the story, because in the movie they never actually do anything -- the Americans just THINK they have, but they're wrong. Joshua/WOPR isn't the enemy either; it's just doing what it's been programmed to do.
The closest thing to a "villain" is probably McKittrick, but his sin as the villain is limited to putting too much trust in the computer system he oversees. He basically ends up being wrong about everything, every step of the way. But at the end, at least he redeems himself. He shakes Falken's hand -- his "sensei", if you will -- out of respect and thanks. And while one would think he might be pissed at David for making him look bad, he tousles David's hair as a "you're alright, kid" gesture to him. Besides, when they first get the indication that the incoming Soviet missiles aren't real, he looks distraught and relieved.
One of the most interesting characters is General Beringer. He's prepared to destroy the Soviets, which is exactly what his job requires of him -- he shouldn't be in that position if he isn't. But he's not a demagogue, and he's not beyond listening to reason. He wants nuclear weapons in the hands of people rather than machines, and his concern on this turns out to be well-founded. When he declares Defcon One, he looks genuinely anxious and appropriately solemn. When Falken explains convincingly why the supposed Soviet attack can't be real because it doesn't make any sense, Beringer listens and ultimately agrees -- knowing that, as the person who will advise the President and on whose advice the President will issue the fateful order, he's basically the most powerful person on earth at that moment. He alone devises the method by which they'll determine if the attack is real or not (getting the senior controllers at the first three US impact targets on the radio while ordering readiness to launch missiles if they lose radio contact), and when it's clear the attack isn't real, he's overjoyed. Basically, throughout the movie his instincts and decisions are correct on the basis of his job and the information at his disposal.
Revenge is a dish best served cold.
-- Klingon proverb