Politics and The Prisoner's Dilemma

I've always been interested in The Prisoner's Dilemma, and how it relates to real life situations, specifically politics. (Don't worry, I'm not going in to specific political situations here.)
You've probably heard of The Prisoner's Dilemma before, but I'll give a quick rundown anyway.

Two criminals are brought back to a police station for interrogation. They're questioned in separate rooms, and each is offered the same deal by the police. The deal is as follows:
If you act as a state's witness and help us convict your friend (assuming he doesn't confess), then you will go free, and your friend will get twenty years in prison. On the other hand, if you don't confess and your friend does, then he will go free and you will get twenty years. If you both confess, then you both get ten years in prison. (The implied statement here is that if neither of them confesses, the state has no case against them and both of them go free).

Naturally, the prisoner starts to look at this from a personal gain perspective: If his friend confesses, then it's better for him to confess as well to get a reduced sentence. If his friend doesnt confess and he does, he can go free. The problem with this selfish type of thinking is that the other person is playing the same game, and when both people are playing this game from a personal gain perspective, it's impossible for either of them to win the ultimate payoff, and go free. However, if both of them took a step back and played from a group perspective, they can both be silent and the state wouldn't have a case against either of them. Rather than take the proactive approach to protect themselves from the other prisoner, each of them could have assumed that the other is playing for the good of the group. And if they had both assumed this and stayed silent, they both would have won. It's when fear and proactive "self-defense" come in to play that the game becomes lose-lose.
I guess the question then becomes (as it relates to politics and war, etc) at what point does proactive self-defense (i.e. attacking the bad guy BEFORE the bad guy can attack us) turn full circle and make us the bad guy? Is our anticipation of attack actually a self-fulfilling prophecy?
Think about how many aspects of life we can relate to this scenario...