The Requirements Engineering (RE) community recognizes the importance of trust proposing several approaches to model and analyze trust requirements. However, such approaches mainly focus on trust as social relations without relating them to the requirements of the system’s components. We propose a belief-based trust approach based on an extended version of Secure Tropos, where social relations are modeled and analyzed along with beliefs concerning capabilities and motivations of system’s components. An example concerning US stock market crash (the Flash Crash) is used to illustrate our approach.