Cargo containers which transport 90 percent of the world's trade transit the countries of the world daily. Despite the vulnerability of cargo containers, only about 5 percent of the over 10 million cargo containers entering the U.S. each year can be inspected now. Our primary goal is to develop the smart container security system using RFID and Wireless Sensor Networks in order to enhance the cargo container security. In addition, the end-to-end visibility via this networked tracking and sensing capability can bring additional commercial benefits to supply chain and chain of custody. In this paper, we first propose a dynamic mesh container network among neighboring containers. Since a group of containers moves together, we can take advantages of interaction between them via this mesh container network instead of focusing an individual container. Second, we introduce the concept of Mobile Edge Computing Devices (MECD) which is the interface between distributed sensors and the end server in order to reduce processing and band width requirements to the end servers. MECDs can give scalability, flexibility, reliability, and cost-efficiency to our cargo container security system.