Racism continued as a sometimes expressed element in American foreign policy through the 1920s and 1930s. World War II, however, set in motion events that resulted in a change in attitude on race both domestically and in foreign policy. Ambivalence on racial issues marked the U.S. record during the war. On the one hand, the tradition of white supremacy and racial prejudice, enforced through segregation, in many ways remained the standard of race relations in American society. Following the Japanese attack on Pearl Harbor, Hawaii, on 7 December 1941, some 112,000 Japanese Americans living in the western states were arrested and removed to a series of "relocation centers" in isolated interior locations. Two-thirds of this group were U.S. citizens, and most of the rest had been denied the right of citizenship because they were not born in the country. The sole criterion for removal was their Japanese ancestry.
Military service was rigidly segregated by race and defined the nonwhite soldier as inferior in every way. Decorated war heroes returned to a society in which they could not get a haircut from a white barber if their skin was not white. However, World War II also proved to be the cauldron from which dramatic changes in race relations would come forth. The beginning of the modern civil rights movement can be traced to the national wartime experience, and these domestic events, as well as the imperative of dealing with a different world, would influence changes in how U.S. foreign policy would deal with racial issues in international affairs.
The world order that emerged from the war was one in which a handful of western European nations no longer were supreme over the majority of the world's populations. The United States, emerging as the single most powerful economic and military nation, found it was in its own interest to distance itself from the racism with which Western nations had been identified. It was essential to Washington that a distinction be drawn between current American policies and association with the European legacy of colonialism, antinationalism, and racism. Interacting with a world no longer predominantly white or European, American policy distanced itself as much as it could from the influence of racism in its past.
Although this new emphasis was pragmatic in nature, it also was shaped by undeniable changes in attitude toward race that were occurring in American society. By the end of the 1960s, the colonies once held by European nations had largely disappeared. Nonwhite populations were assuming control of their own fate around the world, and proponents of white supremacy were increasingly on the defensive. During the war the United States had condemned the racism inherent in Nazi German society. Postwar policies increasingly reflected a condemnation of racial prejudice.
In planning for a continued global American presence, the reality was that the governments and populations with which the United States would deal were inevitably going to be nonwhite. In the presidencies of Harry Truman (1945–1953) and Dwight D. Eisenhower (1953–1961), nationalism among the nonwhite populations of the world was publicly acknowledged to be a force that the United States supported. Although the administrations did not always back up their rhetoric on nationalism with action, there were important examples of the United States supporting nationalistic aspirations of nonwhite populations at the expense of traditional European allies. One such example was Eisenhower's decision during the 1956 Suez crisis to side with the cause of Arab nationalism at the expense of British and French interests.