Identifying threat scenarios and assigning them a probability of occurrence (feasibility) is the essence of a TARA. In this chapter, we address several key challenges in performing TARA. We describe how to actually perform threat identification and discuss the various popular threat modeling approaches. We also discuss which threat catalogs to use and how to use them. We look at the attack paths and discuss the technical depth required and how to perform the attack feasibility evaluation. We conclude the chapter with our three real-world case studies.