In this paper, we propose a novel approach to enterprise mission modeling and mission-centric decision support for cybersecurity operations. The goal of the decision support analytical process is to suggest an effective response for an ongoing attack endangering established mission security requirements. First, we propose an enterprise mission decomposition model to represent the requirements of the missions' processes and components on their confidentiality, integrity, availability. The model is illustrated in a real-world scenario of a medical information system. Second, we propose an analytical process that calculates mission resilience metrics using the attack graphs and Bayesian network reasoning. The process is designed to help cybersecurity operations teams in understanding the complexity of a situation and decision making concerning requirements on enterprise missions.As the IT infrastructures grow larger, it is more and more complicated to protect them and all their components. The insufficient workforce in cyber security and the risks of misunderstanding between security operations and management further underline the problem. The security teams are not always aware of all the missions in an organization, nor knowing about missions' priorities. Under such circumstances, the risk of unwanted actions rises. For example, dropping network traffic of an infected system interrupts operations of a critical IT system or one of its dependencies, which ARES '