Radio links are used to provide backhaul connectivity for base stations of mobile networks, in cases in which cable-based alternatives are not available and cannot be deployed in an economic or timely manner. While such wireless backhauls have been predominantly used in redundant tree and ring topologies in the past, mobile network operators have become increasingly interested in meshed topologies for carrier-grade wireless backhauls. However, wireless mesh backhauls are potentially more susceptible to security vulnerabilities, given that radio links are more exposed to tampering and given their higher system complexity. This article extends prior security threat analyses of 3rd generation mobile network architectures for the case of wireless mesh backhauls. It presents a description of the security model for the considered architecture and provides a list of the basic assumptions, security objectives, assets to be protected and actors of the analysis. On this foundation, potential security threats are analyzed and discussed and then assessed for their corresponding risk. The result of this risk assessment is then used to define a set of security requirements. Finally, we give some recommendations for wireless mesh backhaul designs and implementations following these requirements.