This paper will discuss the role of modality in UN Security Council resolutions. As a work in progress on whether the use of strategic vagueness in UN resolutions has contributed to the outbreak of the second Gulf war, this work proposes a qualitative and quantitative analysis on the role of vagueness of the central modal verbs shall, should, and may in the institutional language of the UN, drawing upon Wodak’s Discourse-Historical Approach and Jenkins, Gotti, and Trosborg's theories on modality. Observing (...) the semantic and linguistic values of these modals, the analysis investigates their double-faced strength: though they can be used to guarantee a wide degree of applicability of the resolutions, their subjective interpretability might become a source of manipulation and elusiveness, supporting a legislative intent of using vagueness as a political strategy. (shrink)