In an interview in the summer of 1965, McGeorge Bundy, a former Harvard dean who served John Kennedy and Lyndon Johnson as national security adviser and was an architect of the Americanization of the Vietnam War, was asked what was different in the actual conduct of American diplomatic affairs from how it had seemed to be "from the safety of Harvard Yard." According to the interviewer, Bundy replied that the first thing that stood out was "the powerful place of domestic politics in the formulation of foreign policies."
It was a revealing comment, but not a surprising one (except to the extent that officials seldom make this admission on the record). The relationship between domestic politics and foreign policy has been an intimate one throughout the nation's history. It may be debated whether the connection is a good thing or a bad thing—whether overall it has been beneficial to the nation's record on the world stage. For the moment, though, it is enough to say that the connection is there and is important. Just why so many students of American diplomacy seemingly have lost sight of this reality over the years is somewhat of a mystery. Partly, the inattention can be explained by the historiographical trends outlined early in this essay, which moved many diplomatic historians away from giving serious and sustained attention to domestic politics. Partly, too, it may reflect an overreliance by scholars on official U.S. government documents in their research; essential though these documents are, they can mislead. American statesmen have always been averse to admitting, even to themselves, that their foreign policy decisions could be affected by private political interest. As a result, a reader of the vast archival record, finding little or no evidence of partisan wrangling or election year strategizing, could (wrongly) conclude that these must have mattered little in shaping American policy.
Whatever the case, it is clear that the influence of party politics on the American approach to international affairs needs to be identified, measured, and explained. Foreign policy, it turns out, is always a political matter. It is not always a crass partisan matter. It is well to remember that the parties historically have tended to speak for different constellations of values and interests, different constituencies with genuine philosophical differences about America's place in the world, and that those differences have sometimes also been evident within parties. But it is always political.