States in competition with each other have powerful incentives to engage in deception. Adversaries use deception to convince each other that their resolve is high and that they possess powerful military capabilities.[1] More puzzling is why states that are aligned with each other—which is understood as “a set of mutual expectations between two or more states that they will have each other’s support in disputes or wars with particular other states”[2]—engage in deception. Aligned states would seem, at first glance, to have good reasons to share information about their intentions and plans with each other comprehensively. This sharing facilitates coordination policies towards a common foe and makes joint action more effective. Such comprehensive sharing of information does occur, but on some occasions aligned states withhold valuable information from each other or deliberately lie about their intentions and capabilities. Perhaps the most notorious recent example is the George W. Bush administration’s exaggeration of claims that Iraq possessed a weapons of mass destruction program, which had the goal of persuading aligned states such as Britain, France, and Saudi Arabia to support military action against the country.[3]
