The connected autonomous vehicle (CAV) will never be completely autonomous; on the contrary, it will be heavily dependent on so-called vehicular ad hoc networks (VANETs) for its function. To deserve the trust of the general public, the vehicles as well as the intelligent transport system (ITS) infrastructure must be able to handle not only natural disturbances but also attacks of malicious nature. In this paper, we discuss the effects of antagonistic attacks using intentional electromagnetic interference (IEMI) and how the antagonistic nature of the threat renders probabilistic risk analysis inadequate for the defense of the vehicles and the infrastructure. Instead, we propose a shift toward resilience engineering and vulnerability analysis to manage antagonistic threats. Finally, we also give two examples of possible scenarios to illustrate the type of situations a CAV must be able to handle.