Mobile ad hoc network (MANET) has a distributed and uncontrolled nature in which all nodes are considered trusted and contribute in the route discovery process. Accordingly, MANET is vulnerable to many types of routing attacks. One of the most popular MANET routing protocol that is vulnerable to different attacks is ad hoc on demand distance vector (AODV) routing protocol. In this paper, a mobile backbone network of trusted nodes is proposed to enhance AODV security with minimum overhead. The proposed backbone network does not violate the MANET mobility characteristic. It is constructed from randomly moving regular MANET nodes based on their trust value, location, and power. The backbone network monitors regular nodes as well as each other to periodically estimate monitoring trust values which represent the reliability of each node in the network. The simulation results show that the backbone network is trustable, has dynamic behavior, and has good coverage.