Why do aligned states sometimes disclose secret information about their miitary plans to use force, whereas other times they choose to deceive their partners? The state initiating these plans may choose among four information-sharing strategies: collusion, compartmentalization, concealment, and lying. Three main considerations shape its decision: the state's assessment of whether it needs its partner's capabilities to succeed at the military mission, the state's perception of whether the partner will be willing to support the state in the requested role, and the state's anticipated deception costs for not fully informing its partner state. Several cases illustrate how these strategies are chosen: Israel, Britain, and France's decision to use force against Egypt during the Suez Crisis (collusion between France and Israel, and concealment vis-à-vis the United States); Israel's 2007 bombing of Syria's al Kibar reactor (compartmentalization); and Israel's deliberations whether to attack Iran's nuclear reactor (lying). These strategies have implications for intra-alliance restraint and contribute to understanding deception and secrecy between allies.