On October 12, 2000, Navy destroyer USS Cole was attacked in the port of Aden, Yemen, demonstrating the dangers of unconventional threats against United States targets in seaports overseas. The current report by the United States General Accounting Office (GAO) was motivated by this attack and recommends specific actions designed to improve the antiterrorism planning of the Southern Command, which is responsible for protecting Department of Defense (DOD) in-transit vessels in overseas ports. In order to make recommendations on the improvement of security for in-transit vessels, the GAO evaluated antiterrorism efforts at three seaports from February 2003 through August 2003. The report includes background information regarding DOD’s antiterrorism policy and guidance, a description of key military commands, and an analysis of the gaps that exist in the Southern Command’s antiterrorism approach, which relies on individual ship force protection plans and excludes voyage charter vessels. The GAO report identifies opportunities for the improvement of the Southern Command’s antiterrorism approach. Such opportunities involve the use of two key mechanisms: working groups and periodic reviews. Specifically, the GAO recommends clarifying and delineating responsibilities for voyage charters, implementing a forum for the review of antiterrorism measures for in-transit forces, and developing a periodic oversight system. The DOD generally agreed with these recommendations in written comments of this report. Appendices include descriptions of the scope and methodology of the evaluation, DOD’s risk management approach, DOD comments, and GAO contact and staff information. Tables, figures, appendix