We are in an adversarial relationship with everyone else, even allies, because our interests are not identical. Game theory says there's value in unpredictabil

We are in an adversarial relationship with everyone else, even allies, because our interests are not identical. Game theory says there's value in unpredictability. Optimal strategies in games can involve randomness. To the extent we are credible, this reduces our unpredictability. In the specific example of defending Europe, our credibility enables Europe to adopt a strategy of sponging off the US. Arguably the US would be better off if there was more doubt in Europe about whether we'd actually follow through on commitments.