Washington's option for the first-use of nuclear weapons, and its connected stance on 'negative security assurances', is largely based on the idea these weapons serve a wider purpose than deterring nuclear attack. During the Cold War this wider purpose was mostly seen as deterring a Soviet conventional invasion of Western Europe; today, this wider purpose is less clear and less defined or constrained by strategic logic. The idea of 'calculated ambiguity' has been used to explain the situation, but it is inadequate. It fails to capture the way the controversy surrounding the first-use option occupies the intersection of planning for nuclear war, putative US national interests, arms control, contrasting conceptions of world order, and foreigners' perceptions of the United States.