Is American foreign policy predictable?

Yes and No. I sometimes ask my students what foreign leaders want to know about the United States and where they might get that information. Our society is so open -- exposed, really -- that outsiders can easily find out what officials say and what key institutions are doing. And yet, even our most plugged-in journalists can't predict how President Obama will act in Syria or Ukraine next week.

Winston Churchill claimed there was a regular pattern to U.S. behavior. He is said to have said -- by second-hand sources; no documentation exists; but the idea is too clever not to quote -- that "the Americans can always be counted on to do the right thing in the end, after exhausting all other possibilities."

An alternative point of view was expressed by senior foreign office officials in March, 1939, in a delicious quote cited by British historian David Reynolds: Predicting the course of U.S. foreign policy is "as simple as trying to weigh a wild cat on the kitchen scales."

Reynolds himself, looking at Anglo-American relations 1937-41, says U.S. policymakers "tended towards anglophilia culturally and anglophobia politically."

That's why granular predictions are hard: there are always cross-pressures and trade-offs that influence particular decisions. Even if the grand strategy is clear [itself a rarity in the American political system], its application to complex situations like Iran or China is not easily predictable.