...thereby punctuating, with mushroom-shaped exclamation points, the end of a world conflict notable not only for its immense scale and destructiveness but also for the extent to which the major combatants had come to regard massive attacks on civilian populations as a permissible means of waging war.

The nuclear attacks on Hiroshima and Nagasaki, although they were hardly the first instances of wholesale devastation of cities in World War 2, did demonstrate a terrible new level of technological efficiency in the implementation of the "strategic bombing" approach to warfare which that conflict had spawned. The two nuclear bombings also provided the underpinnings of a post-war U.S. security policy based on nuclear deterrence -- that is, on the idea that the United States might well be willing to use against others the same awesome capacity for nuclear destruction that it had used against Japan in August of 1945.