The John A. Volpe National Transportation Systems Center was asked by the Office of Security of the Maritime Administration to examine the issue of industrial control systems (ICS) security in the Maritime Transportation System (MTS), and to develop a white paper based upon its findings for circulation amongst MTS stakeholders. In evaluating the issue, this paper first discusses the role of the MTS as part of the domestic and international transportation system and global supply chain, and provides examples of the economic impact of past natural and manmade disruptions to the MTS. It next explores the uses and applications of ICS throughout the MTS, identifies potential cybersecurity vulnerabilities of ICS, and provides examples of possible ICS failures and the potential impact on the MTS. Finally, the paper explores the issue in the context of Federal policy governing critical infrastructure, cybersecurity and supply chain resilience, and makes a number of recommendations that government agencies and the private sector might consider in order to mitigate the ICS security risks.