Explanations that focus on norms, ideology, and domestic sources of foreign policy are increasingly popular in studies of international politics during the Cold War. This article finds that U.S. policy in the early 1950s was driven chiefly by structural factors, especially the changing balance of power. What appeared to be a radical shift in policy toward Iran initiated by Eisenhower was, in fact, largely a continuation of the policies of the Truman administration, with new options made possible by the h uge U.S. military buildup of the early 1950s.