There has been no use of nuclear weapons since Hiroshima and Nagasaki. Nina Tannenwald argues that this was not inevitable, but that a tradition of non-use of nuclear weapons has grown up, a tradition that is not simply explained by theories of deterrence. This tradition is based on the feeling that nuclear weapons are not a legitimate weapon of war, a feeling which has grown stronger as nuclear arsenals have become ever more deadly. Tannenwald illustrates her argument by examining the nuclear experience of the United States since 1945.